Functionalized polymers

ABSTRACT

This document relates to functionalized (e.g., mono- or bi-functional) polymers (e.g., polyethylene glycol and related polymers) as well as methods and materials for making and using such functionalized polymers.

CLAIM OF PRIORITY

This application is a continuation of U.S. application Ser. No.16/186,900, filed Nov. 12, 2018, which is a continuation of U.S.application Ser. No. 15/727,706, filed Oct. 9, 2017, now U.S. Pat. No.10,125,220, which is a continuation of U.S. application Ser. No.14/499,354, filed Sep. 29, 2014, now U.S. Pat. No. 9,790,324, which is acontinuation application of U.S. application Ser. No. 13/324,872, filedDec. 13, 2011, now U.S. Pat. No. 8,846,941, which claims priority toSwedish Patent Application Serial No. 1001187-2, filed on Dec. 13, 2010,the entire contents of which are hereby incorporated by reference.

TECHNICAL FIELD

This document relates to functionalized (e.g., mono- or bi-functional)polymers (e.g., polyethylene glycol and related polymers) as well asmethods and materials for making and using such functionalized polymers.

BACKGROUND

Pharmacokinetic and immune stimulating properties of proteins andsynthetic drugs may be controlled by their conjugation to certainpolymers. For example, polyethylene glycol (PEG) can be conjugated toproteins to achieve this effect (Fee and Van Alstine, ChemicalEngineering Science, 61:924-934 (2006)). Such conjugation can take placeif the relatively non-reactive hydroxyl groups present in PEG moleculesare substituted by other, more reactive moieties (Jagur-Grudzinski,Reactive & Functional Polymers, 39:99-138 (1999)). A standard, linearPEG molecule is chemically a diol, which could suggest that the processof PEG derivatization and purification of products should be trivial.However, the polymeric nature of this diol, together with itsamphiphilic properties can make these manipulations difficult. In somecases, the typical laboratory process for separation of difficultreaction mixtures, silica gel-based flash column chromatography, canfail for PEG with molecular weight higher than 1000. Neithercrystallization nor precipitation appear adequate to achieve separationof PEG-containing materials, even if these methods can be used forefficient removal of other, contaminating substances with low molecularweight. Most reaction mixtures containing modified PEG molecules lack areliable analytical method to control or to prove their composition.Polymers with functions that influence only minimally the hydrophobicproperties of the polymer can be difficult to analyze by chromatography.The same applies for polymers with functions carrying only a minimalcharge. This also applies for preparative chromatographic separation ofcharged polymers as described elsewhere for the separation of mono- anddi-carboxyl modified PEG molecules (Drioli et al., Reactive & FunctionalPolymers, 48:119-128 (2001)).

Confirmation of results of the synthesis based on NMR can be useless, aslong as one is not sure about the purity of the product, and this istypically only obtained by chromatographic methods. This unusualconclusion comes from observations that an equimolar mixture ofnon-derivatized polymer and bis-derivatized polymer will produce an NMRpattern identical to the pure mono-derivatized polymer. Massspectrometry can be complicated since most PEG exists not in the form ofa single component, but is rather a Gaussian population of differentpolymer lengths, centered on its average molecular weight. Thus, even ifall distinct components of the same type should have their massincreased by the same factor, the presence of unreacted and bis-modifiedmaterial can obscure the picture of the analysis. The literaturediscusses this problem only sporadically, and often nothing is mentionedabout analysis of the product or its purification. Many authors make theimpression that the process that they describe is ongoing withquantitative yield, and thus the quality of the product does not need tobe analyzed or questioned. This non-scientific approach can befrequently encountered in the chemistry of PEG. There are many examplesin the literature presenting synthetic procedures with four to fiveconsecutive steps without a single analysis of the product at any ofthese steps, without any attempts to purifying the product, and assuming100 percent purity at the end of the process. It is, therefore, notstrange that researchers after closer testing question these productsand their purity (Ananda et al., Anal. Biochem., 374, 231-242 (2008)). Acommonly accepted escape from the problem of selective modification isto work with a polymer that has one end blocked from the beginning by astable chemical group, most often a methoxy group (mPEG). In theory,this blockage converts a PEG molecule to a monofunctional compound, andas such, it could be fully converted to the second derivatized form byincreasing the amount of derivatizing reagent and/or time for reaction.Unfortunately, many of reactions commonly applied for derivatization ofPEG are sluggish and only seldom go to completion. On the other hand,mPEG preparations contain significant percentages of PEG diol component.Moreover, the amount of this contamination increases with the length ofmPEG, and this contamination can be hard to avoid. Consequently,derivatization will also result in formation of symmetrical,bis-derivatizated PEG, and its presence in the conjugating mixtureresults in formation of cross-linked products with unknown pharmacologicproperties or a possible loss of protein activity. Therefore, pure,monofunctional polymers are usually preferred for protein modification,but one should be aware that purification of mPEG from its diol PEGcontamination is practically impossible.

Nearly all of existing reactions, used today for derivatization of PEG,belong either to the alkylation-based or the acylation-based category.In the first case, the alkoxy anion, generated from PEG, is reactingwith incoming electrophilic modifying reagent. Eventually, the activatedPEG, subjected with a good leaving group, is itself an object of anucleophilic attack. To this category belong processes resulting inthiolation, amination, azidation, and introduction of a carboxyl or analdehyde group. Modified PEG'S of this category will have theirfunctional group connected directly to the PEG terminal carbon atom orthese groups will be linked via an ether bond, a thioether bond, or asecondary amino group.

The second category, acylation, is based on a nucleophilic reaction ofPEG's hydroxyl, (or another group present in a modified PEG—often anamino group), on an incoming acylating reagent. In many cases, thisfirst acylation is followed by a second acylation that actuallyintroduces the modification of interest to the PEG molecule. Functionalgroups incorporated by this method can be linked to the rest of PEG byan amido, a carbamido, urethane, thiourethane, or a simple ester group.These linking groups and the chemistry behind them belong to the verytraditional methods of combining two chemical identities.

Polyethylene glycols (PEG) coupled to phosphoramidites are used fordirect coupling of PEG molecules to synthetic nucleic acids. One exampleis4,4′-dimethoxy-trityl-polyethyleneglycol-[(2-cyanoethyl)-(N,N-diisopropyl)]-phosphoramidite.In these compounds, the phosphoramidite group is the part of thereactive functionality for linking the compound to a synthetic nucleicacid. It is designed to work in a completely water-free environment: Inthe presence of water, the phosphoramidite group can decomposeinstantaneously, making such PEG phosphoramidites inappropriate forconjugation to biological material in water-containing or aqueoussolution. In particular, these PEG phosphoramidites can be inappropriatefor conjugation to biological substances which are not soluble, stableor sufficiently reactive in non-aqueous media. Furthermore, alreadymildly acidic biological substances can decompose these PEGphosphoramidites. Finally, these PEG phosphoramidites contain a labileprotecting group adjacent to the phosphorous atom which is speciallydesigned to convert the intermediate phosphotriester to aphosphodiester. Phosphodiesters can be readily degraded enzymatically invivo.

SUMMARY

This document provides functionalized (e.g., mono- or bi-functional)polymers (e.g., polyethylene glycol and related polymers) as well asmethods and materials for making and using such functionalized polymers.The functionalized polymers can be used to conjugate a biologicallyactive molecule, thereby potentially altering the pharmacokinetic andpharmacodynamic profile of the biologically active molecule. Thefunctionalized polymers include one or more linking groups selected froma phosphotriester, a phosphoramidate, a thiophosphotriester, and athiophosphoramidate. For example, this document provides a PEG polymerhaving at least one terminus covalently bound to a phosphotriester orphosphoramidate linking group. A functionalized polymer provided hereincan include different linking groups at each of its termini. Alsoprovided herein is a functionalized polymer modified at at least oneterminus with a blocking group (e.g., methoxy group) and functionalizedat at least another terminus with a linking group as described herein.

As described herein, preparations of a functionalized polymer having oneor more linking groups can be obtained in a manner where greater than 50percent by weight (e.g., greater than 75 percent, greater than 80percent, greater than 90 percent, greater than 95 percent, greater than98 percent, and greater than 99 percent by weight) of the preparation isthe desired functionalized polymer free from contaminants. As a personof ordinary skill in the art would understand, a functionalized polymerpreparation includes a Gaussian population of different polymer lengthscentered on an average molecular weight, and such a functionalizedpopulation would not be considered contaminating. For example, amono-functionalized PEG population can be separated nearlyquantitatively from contaminants of PEG functionalization (e.g.,unreacted PEG and poly-functionalized PEG populations). The separationof a functionalized polymer provided herein can be facilitated throughthe use of a removable hydrophobic separation handle (e.g., asubstituted or unsubstituted trityl group) which upon removal allows forpreparative isolation of product (e.g., pure product), free orsubstantially free from unreacted polymer and poly-functionalizedpolymer.

Having the ability to isolate functionalized polymers in high purity canallow chemists to more easily control subsequent reactions or the purityof the downstream products. In some cases, having the ability tointroduce all functional groups through a unified process using similar,mild reagents and reaction conditions can allow for the production of afunctionalized polymer through a fast and nearly quantitative reaction.

The ability to isolate functionalized polymers quantitatively can allowchemists to more easily control subsequent reactions or the purity ofconjugates of a biologically active molecule coupled to a functionalizedpolymer provided herein.

In addition to increasing the purity of a functionalized polymer, alinking group can act as a linker between the polymer and a biologicallyactive group or a detectable functional group. For instance, afunctionalized polymer of high purity can be coupled to a biologicallyactive molecule or a detectable functional group. In such conjugates,the linker can form covalent bonds to the polymer and a biologicallyactive molecule or a detectable functional group. The coupling can takeplace in an aqueous reaction medium. The biologically active molecule ordetectable functional group can be acidic.

Furthermore, the linking groups provided herein are generally resistantto chemical and enzymatic degradation, providing for more stable storageand increased safety and efficacy in vivo.

Provided herein is a compound comprising a water-soluble, non-peptidic,and non-nucleotidic polymer backbone having at least one terminuscovalently bonded to a structure of formula (1):

or a salt thereof,wherein:

-   A is the point of covalent bonding to the terminus of the polymer    backbone;-   E is O or S;-   K is selected from the group consisting of: alkylene,    alkyleneoxyalkylene, and oligomeric alkyleneoxyalkylene;-   G is selected from the group consisting of: hydrogen, alkoxy, and a    hydrophobic separation handle;-   Z¹ and Z² are independently selected from O and NH, wherein only one    of Z¹ and Z² can be NH;-   L is selected from the group consisting of: a divalent radical of a    nucleoside, alkylene, alkyleneoxyalkylene, oligomeric    alkyleneoxyalkylene, and unsubstituted and substituted arylene;-   M is a protected group that when deprotected is reactive with a    biologically active molecule, a group reactive with a biologically    active molecule, or is a detectable functional group;-   R is absent or selected from the group consisting of: hydrogen, a    protecting group, a hydrophobic separation handle, or an activating    group;-   R¹ is absent or a hydrophobic separation handle;-   wherein when M is a protected group that when deprotected is    reactive with a biologically active molecule, then R is a protecting    group or a hydrophobic separation handle;-   wherein when M is a group reactive with a biologically active    molecule, R is absent, hydrogen, or an activating group; and-   wherein when M is a detectable functional group, R is absent or    hydrogen.

In some embodiments, at least one of R, R¹, and G is a hydrophobicseparation handle. For example, only one of R, R¹, and G can be ahydrophobic separation handle. In some embodiments, the hydrophobicityof one of R or R¹ is higher than the other.

In some embodiments, the polymer backbone has from 2 to 100 termini. Insome embodiments, only one termini of the polymer backbone is covalentlybonded to the structure of formula (1).

In some embodiments, the polymer backbone has two termini. In someembodiments, only one termini of the polymer backbone is covalentlybonded to the structure of formula (1). In some embodiments, bothtermini of the polymer backbone are covalently bonded to the structureof formula (1).

A polymer backbone can be selected from the group consisting ofpoly(alkylene glycol), poly(oxyethylated polyol), poly(olefinicalcohol), poly(α-hydroxy acid), poly(vinyl alcohol), polyoxazoline, andcopolymers. For example, a polymer backbone can be poly(ethyleneglycol). In some cases, a poly(ethylene glycol) has an average molecularweight from about 500 Da to about 100,000 Da.

In some embodiments, one of Z¹ and Z² is NH and the other is O. In someembodiments, Z¹ is O and Z² is NH. In some embodiments, Z¹ is NH and Z²is O. In some embodiments, both Z¹ and Z² are O.

A group reactive with a biologically active molecule can be selectedfrom the group consisting of: hydroxyl, amine, thiol, carboxyl,aldehyde, glyoxal, dione, alkenyl, alkynyl, alkedienyl, azide,acrylamide, vinyl sulfone, hydrazide, aminoxy, maleimide,dithiopyridine, iodoacetamide.

In some embodiments, K is selected from the group consisting of:methylene, ethylene, propylene, isopropylene, butylene, isobutylene,sec-butylene, tert-butylene, and hexylene, or a residue from diethyleneglycol, triethylene glycol, tetraethylene glycol or hexaethylene glycol.

In some embodiments, G is a substituted or unsubstituted trityloxy.

In some embodiments, L is a substituted or unsubstituted C₁-C₁₂alkylene.

In some embodiments, R is selected from the group consisting of: trityl,monoalkoxytrityl, dialkoxytrityl, pixyl, alkoxypixyl,fluorenylmethyloxycarbonyl, trifluoroacetyl, acetal, and cyclic acetal.

In some embodiments, a group reactive with a biologically activemolecule is carboxyl and R is absent or selected from the groupconsisting of: chlorotrityl, trityl, N-hydroxysuccinimidyl,p-nitrophenyl, pentachlorophenyl, and an unsubstituted C₁-C₁₈ alkyl.

Also provided herein is a preparation comprising a compound comprising awater-soluble, non-peptidic, and non-nucleotidic polymer backbone havingat least one termini covalently bonded to a structure of formula (1):

or a salt thereof, wherein the preparation comprises at least 50% byweight of the compound. In some embodiments, the compound is essentiallypure.

Further provided herein is a method for making a compound of claim 1,said method comprising: contacting a water-soluble, non-peptidic, andnon-nucleotidic polymer, in a water-free solvent, with a reagent offormula (4):

wherein:

-   R⁵ and R⁶ independently from each other represent C₁-C₆-alkyl or R⁵    and R⁶ jointly form a 5- or 6-membered ring with the N to which they    are bonded;    adding an activating reagent; and adding an oxidizing reagent,    wherein the P is oxidized from P⁺³ to P⁺⁵.

In some embodiments, R is a protecting group.

In some embodiments, the method further comprises purifying theprotected polymer by chromatography. In some embodiments, the methodfurther comprises removing the protecting group.

An activating reagent can be selected from the group consisting of:tetrazole, 2-ethylthiotetrazole, 2-bezylthiotetrazole,4,5-dicyanoimidazole, Activator 42, pyridinium hydrochloride, andpyridinium trifluoroacetate. An oxidizing reagent can be selected from agroup consisting of: iodine, hydrogen peroxide, t-butyl hydrogenperoxide, acetone peroxide, sulfur, and thiuram disulfide. In someembodiments, the ratio of the polymer to the compound of formula (4) isfrom about 1:10 to about 10:1.

A compound provided herein can be used in a conjugate, or apharmaceutically acceptable salt thereof, comprising a compound and abiologically active molecule. Such a conjugate can be prepared byconjugating the compound to a biologically active molecule.

Provided herein is a compound of formula (2):

or a salt form thereof,wherein:

-   polymer is a linear, water-soluble, non-peptidic, and    non-nucleotidic polymer backbone, wherein each linking group is    bonded at a different terminus of said polymer;-   E and E¹ are independently O or S;-   K and K₁ are independently selected from the group consisting of:    alkylene, alkyleneoxyalkylene, and oligomeric alkyleneoxyalkylene;-   G and G₁ are independently absent or are selected from the group    consisting of: alkoxy and a hydrophobic separation handle;-   each pair of Z¹ and Z² and Z³ and Z⁴ are independently selected from    O and NH, wherein only one of each pair of Z¹ and Z² and Z³ and Z⁴    can be NH;-   L and L¹ are independently selected from the group consisting of: a    divalent radical of a nucleoside, alkylene, alkyleneoxyalkylene,    oligomeric alkyleneoxyalkylene, and unsubstituted and substituted    arylene;-   M and M¹ are independently selected from a protected group that when    deprotected is reactive with a biologically active molecule, a group    reactive with a biologically active molecule, or is a detectable    functional group, wherein M and M¹ are different; and-   R and R¹ are independently absent, hydrogen, a protecting group, or    an activating group; wherein when M is a protected group that when    deprotected is reactive with a biologically active molecule, then R    is a protecting group or a hydrophobic separation handle;-   wherein when M is a group reactive with a biologically active    molecule, R is absent, hydrogen, or an activating group;-   wherein when M is a detectable functional group, R is absent or    hydrogen;-   wherein when M¹ is a protected group that when deprotected is    reactive with a biologically active molecule, then R¹ is a    protecting group or a hydrophobic separation handle;-   wherein when M¹ is a group reactive with a biologically active    molecule, R¹ is absent, hydrogen, or an activating group; and-   wherein when M¹ is a detectable functional group, R¹ is absent or    hydrogen.

In some embodiments, one of Z¹ and Z² is NH and the other is O. In someembodiments, Z¹ is O and Z² is NH. In some embodiments, Z¹ is NH and Z²is O. In some embodiments, both Z¹ and Z² are O. In some embodiments,one of Z³ and Z⁴ is NH and the other is O. In some embodiments, Z³ is Oand Z⁴ is NH. In some embodiments, Z³ is NH and Z⁴ is O. In someembodiments, both Z³ and Z⁴ are O.

In some embodiments, a group reactive with a biologically activemolecule is independently selected from the group consisting of:hydroxyl, amine, thiol, carboxyl, aldehyde, glyoxal, dione, alkenyl,alkynyl, alkedienyl, azide, acrylamide, vinyl sulfone, hydrazide,aminoxy, maleimide, dithiopyridine, iodoacetamide.

In some embodiments, K and K¹ are independently selected from the groupconsisting of: methylene, ethylene, propylene, isopropylene, butylene,isobutylene, sec-butylene, tert-butylene, and hexylene, or a residuefrom diethylene glycol, triethylene glycol, tetraethylene glycol orhexaethylene glycol.

In some embodiments, G and G¹ is independently selected from asubstituted or unsubstituted trityloxy.

In some embodiments, L and L¹ is independently a substituted orunsubstituted C₁-C₁₂ alkylene.

In some embodiments, R or R¹ is independently selected from the groupconsisting of: trityl, monoalkoxytrityl, dialkoxytrityl, pixyl,alkoxypixyl, fluorenylmethyloxycarbonyl, trifluoroacetyl, acetal, cyclicacetal, and combinations of thereof.

In some embodiments, the polymer is poly(ethylene glycol). For example,a poly(ethylene glycol) having an average molecular weight from about500 Da to about 100,000 Da.

Also provided herein is a preparation comprising a compound of formula(2):

or a salt form thereof, wherein the preparation comprises at least 50%by weight of the compound.

Further provided herein is a method for making a compound of formula(2), the method comprising: reacting a linear, water-soluble,non-peptidic, and non-nucleotidic polymer, in a water free solvent, witha reagent selected from the group consisting of a compound of formula(5):

wherein:

-   R⁵ and R⁶ independently from each other represent C₁-C₆-alkyl or    jointly form a 5- or 6-membered ring, and a compound of formula (6):

wherein:

-   R⁷ and R⁸ independently from each other represent C₁-C₆-alkyl or R⁷    and R⁸ jointly form a 5- or 6-membered ring with the N to which they    are bonded;    under conditions that facilitate formation of monoderivatized    product; and reacting the monoderivatized product with a reagent    selected from the group consisting of a compound of formula (5) and    a compound of formula (6), wherein the reagent is different from the    reagent from step a); under conditions that facilitate conversion to    the compound.

In some embodiments, the method further comprises isolating themonoderivatized product using by chromatography prior to reacting themonoderivatized product.

In some embodiments, the conversion to the compound is quantitative.

In some embodiments, R is a hydrophobic separation handle. In someembodiments, the method further comprises removing the hydrophobicseparation handle and isolating the compound by precipitation orcrystallization.

A compound of formula (2) provided herein can be used in a conjugate, ora pharmaceutically acceptable salt thereof, comprising a compound and abiologically active molecule. Such a conjugate can be prepared byconjugating the compound to a biologically active molecule.

Also provided herein is a compound of formula (3):

or a salt form thereof,wherein:

-   polymer is a linear, water-soluble, non-peptidic, and    non-nucleotidic polymer backbone, wherein M² and the    phosphonate-derived functional group are bonded at a different    terminus of said polymer;-   E and E¹ are independently O or S;-   K is selected from the group consisting of: alkylene,    alkyleneoxyalkylene, and oligomeric alkyleneoxyalkylene;-   G is selected from the group consisting of: hydrogen, alkoxy, and a    hydrophobic separation handle;-   Z¹ and Z² are independently selected from O and NH, wherein only one    of Z¹ and Z² can be NH;-   L is selected from the group consisting of: a divalent radical of    nucleoside, alkylene, alkyleneoxyalkylene, oligomeric    alkyleneoxyalkylene, and unsubstituted and substituted arylene;-   M is selected from a protected group that when deprotected is    reactive with a biologically active molecule, a group reactive with    a biologically active molecule, or is a detectable functional group;-   M² is selected from O, S or NH; and-   R is absent, a protecting group, a hydrophobic separation handle, or    an activating group;-   R² is hydrogen or a protecting group;-   wherein when M is a protected group that when deprotected is    reactive with a biologically active molecule, then R is a protecting    group or a hydrophobic separation handle;-   wherein when M is a group reactive with a biologically active    molecule, R is absent, hydrogen, or an activating group; and-   wherein when M is a detectable functional group, R is absent or    hydrogen.

In some embodiments, one of Z¹ and Z² is NH and the other is O. In someembodiments, Z¹ is O and Z² is NH. In some embodiments, Z¹ is NH and Z²is O. In some embodiments, both Z¹ and Z² are O.

A group reactive with a biologically active molecule can be selectedfrom the group consisting of: hydroxyl, amine, thiol, carboxyl,aldehyde, glyoxal, dione, alkenyl, alkynyl, alkedienyl, azide,acrylamide, vinyl sulfone, hydrazide, aminoxy, maleimide,dithiopyridine, iodoacetamide.

In some embodiments, K is selected from the group consisting of:methylene, ethylene, propylene, isopropylene, butylene, isobutylene,sec-butylene, tert-butylene, and hexylene, or a residue from diethyleneglycol, triethylene glycol, tetraethylene glycol or hexaethylene glycol.

In some embodiments, G is a substituted or unsubstituted trityloxy. Forexample, G can be a monoalkoxy substituted trityloxy group or a dialkoxysubstituted trityloxy group.

In some embodiments, R² is absent or selected from the group consistingof trityl, monoalkoxytrityl, dialkoxytrityl, pixyl, alkoxypixyl,fluorenylmethyloxycarbonyl, alkylcarboxyl, benzoyl, tetrahydropyranyl,methyl.

In some embodiments, the polymer is poly(ethylene glycol).

Further provided herein is a preparation comprising a compound offormula (3):

or a salt form thereof, wherein said preparation comprises at least 50%of said compound.

A compound of formula (3) can be prepared by reacting a monosubstitutedpolymer comprising a linear, water-soluble, non-peptidic, andnon-nucleotidic polymer backbone bonded at the first terminus with thefunctional group M²-R², with a reagent of formula (5):

wherein:R⁵ and R⁶ independently from each other represent C₁-C₆-alkyl or R⁵ andR⁶ jointly form a 5- or 6-membered ring with the N to which they areattached; under conditions facilitating the quantitative conversion ofsaid monosubstituted polymer to said compound.

In some embodiments, the compound of formula (3) is isolated byprecipitation or crystallization.

In some embodiments, R is a hydrophobic separation handle.

In some embodiments, the method further comprises removal of thehydrophobic separation handle and isolating said compound byprecipitation or crystallization.

A compound of formula (3) provided herein can be used in a conjugate, ora pharmaceutically acceptable salt thereof, comprising a compound and abiologically active molecule. A biologically active molecule can beselected from the group consisting of enzymes, peptides, polypeptides,nucleotides, oligonucleotides, polynucleotides, and therapeutic agentshaving a molecular weight of less than 1000 g/mol. Such a conjugate canbe prepared by conjugating the compound to a biologically activemolecule.

Provided herein is a method of preparing a compound comprising awater-soluble, non-peptidic, and non-nucleotidic polymer backbone havingat least one terminus covalently bonded to a structure of formula (7):

or a salt thereof,wherein:

-   A is the point of covalent bonding to the terminus of the polymer    backbone;-   E is O or S;-   Y represents an optionally substituted residue selected from alkyl,    cycloalkyl, heterocyclyl, aryl, and heteroaryl;-   Z¹ and Z² are independently selected from O and NH, wherein only one    of Z¹ and Z² can be NH;-   L is selected from the group consisting of: a divalent radical of a    nucleoside, alkylene, alkyleneoxyalkylene, oligomeric    alkyleneoxyalkylene, and unsubstituted and substituted arylene;-   M is a biologically active molecule or a detectable functional    group;    comprising the steps of:    providing a compound of formula (8):

wherein:

-   A is the point of covalent bonding to the terminus of the polymer    backbone;-   E is O or S;-   Y represents an optionally substituted residue selected from alkyl,    cycloalkyl, heterocyclyl, aryl, and heteroaryl;-   Z¹ and Z² are independently selected from O and NH, wherein only one    of Z¹ and Z² can be NH;-   L is selected from the group consisting of: a divalent radical of a    nucleoside, alkylene, alkyleneoxyalkylene, oligomeric    alkyleneoxyalkylene, and unsubstituted and substituted arylene;-   M is a protected group that when deprotected is reactive with a    biologically active molecule;-   R is a hydrophobic separation handle;-   R¹ is absent or a hydrophobic separation handle; and    (b) removing the hydrophobic separation handle(s);    (c) optionally reacting the compound obtained in step (b) with an    activating agent; and    (d) reacting the compound obtained in step (b), or, optionally in    step (c), with a biologically active material or the detectable    functional group.

In some embodiments, one of Z¹ and Z² is NH and the other is O. In someembodiments, Z¹ is O and Z² is NH. In some embodiments, Z¹ is NH and Z²is O. In some embodiments, both Z¹ and Z² are O.

The protected group M can be, when deprotected, selected from the groupconsisting of: hydroxyl, amine, thiol, carboxyl, aldehyde, glyoxal,dione, alkenyl, alkynyl, alkedienyl, azide, acrylamide, vinyl sulfone,hydrazide, aminoxy, maleimide, dithiopyridine, iodoacetamide.

In some embodiments, R is selected from the group consisting of: trityl,monoalkoxytrityl, dialkoxytrityl, pixyl, alkoxypixyl,fluorenylmethyloxycarbonyl, trifluoroacetyl, acetal, and cyclic acetal.

In some embodiments, the polymer backbone is selected from the groupconsisting of poly(alkylene glycol), poly(oxyethylated polyol),poly(olefinic alcohol), poly(α-hydroxy acid), poly(vinyl alcohol),polyoxazoline, and copolymers. For example, the polymer backbone can bepolyethylene glycol).

In some embodiments, reaction step (d) is carried out in the presence ofwater or a protic solvent. In some embodiments, the compound of formula(8) is essentially pure. In some embodiments, the biologically activematerial or the detectable functional group reacts acidic in water.

This disclosure utilizes phosphoramidites as reagents interacting withpolymers to form a phosphotriester-type of linker between a polymer andlinking group. A similar process is used commonly in the chemistry ofnucleic acids. Formation of a phosphotriester bond, in the chemistry ofnucleic acids, is often followed by its partial hydrolysis(deprotection) to the phosphodiester bond, because phosphodiester bondsare naturally occurring. The present disclosure provides an uncommon andunnatural phosphotriester linkage which is enzymatically resistant,offering a stable linker between a polymer and a biologically activemolecule.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention pertains. Although methods and materialssimilar or equivalent to those described herein can be used to practicethe invention, suitable methods and materials are described below. Allpublications, patent applications, patents, and other referencesmentioned herein are incorporated by reference in their entirety. Incase of conflict, the present specification, including definitions, willcontrol. In addition, the materials, methods, and examples areillustrative only and not intended to be limiting.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

DETAILED DESCRIPTION

This document provides functionalized (e.g., mono- or bi-functional)polymers (e.g., polyethylene glycol and related polymers) as well asmethods and materials for making and using such functionalized polymers.The functionalized polymers can be used to conjugate a biologicallyactive molecule, thereby potentially altering the pharmacokinetic andpharmacodynamic profile of the biologically active molecule. Thefunctionalized polymers include one or more linking groups selected froma phosphotriester, a phosphoramidate, a thiophosphotriester, and athiophosphoramidate. A functionalized polymer provided herein caninclude different linking groups at each of its termini. Also providedherein is a functionalized polymer modified at at least one terminuswith a blocking group (e.g., methoxy group) and functionalized at atleast another terminus with a linking group as described herein.

For example, this document provides functionalized PEG polymers. In somecases, a functionalized PEG polymer has at least one terminus covalentlybound to a phosphotriester, a phosphoramidate, a thiophosphotriester,and a thiophosphoramidate linking group. For example, a functionalizedPEG polymer can have at least one terminus covalently bound to aphosphotriester or phosphoramidate linking group.

In some cases, a PEG polymer is a linear PEG polymer (i.e., having twotermini). A linear PEG polymer can be functionalized as described hereinat one or both termini with the same or different linking groups. Insome cases, one of the termini of a linear PEG polymer is blocked with ablocking group (e.g., methoxy or a protecting group) and the othertermini is functionalized with a linking group as described herein. Insome cases, one of the termini of a linear PEG polymer is functionalizedwith a phosphotriester linking group and the other termini isfunctionalized with a phosphoramidate linking group. In other cases,both termini are functionalized with the same or differentphosphotriester linking groups. In yet other cases, both termini arefunctionalized with the same or different phosphoramidate linkinggroups.

Definitions

For the terms “for example” and “such as,” and grammatical equivalencesthereof, the phrase “and without limitation” is understood to followunless explicitly stated otherwise. As used herein, the term “about” ismeant to account for variations due to experimental error. Allmeasurements reported herein are understood to be modified by the term“about”, whether or not the term is explicitly used, unless explicitlystated otherwise. As used herein, the singular forms “a,” “an,” and“the” include plural referents unless the context clearly dictatesotherwise.

The term “alkyl” includes straight-chain alkyl groups (e.g., methyl,ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, etc.)and branched-chain alkyl groups (e.g., isopropyl, tert-butyl, isobutyl,etc.). In certain embodiments, a straight chain or branched chain alkylhas twelve or fewer carbon atoms in its backbone (e.g., C₁₋₁₂ forstraight chain; C₃₋₁₂ for branched chain). The term C₁₋₁₂ includes alkylgroups containing 1 to 12 carbon atoms.

The term “alkenyl” includes aliphatic groups that may or may not besubstituted, as described above for alkyls, containing at least onedouble bond and at least two carbon atoms. For example, the term“alkenyl” includes straight-chain alkenyl groups (e.g., ethenyl,propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, anddecenyl) and branched-chain alkenyl groups. In certain embodiments, astraight chain or branched chain alkenyl group has twelve or fewercarbon atoms in its backbone (e.g., C₂₋₁₂ for straight chain; C₃₋₁₂ forbranched chain). The term C₂₋₁₂ includes alkenyl groups containing 2 to12 carbon atoms.

The term “alkynyl” includes unsaturated aliphatic groups analogous inlength and possible substitution to the alkyls described above, butwhich contain at least one triple bond and two carbon atoms. Forexample, the term “alkynyl” includes straight-chain alkynyl groups(e.g., ethynyl, propynyl, butynyl, pentynyl, hexynyl, heptynyl, octynyl,nonynyl, and decynyl) and branched-chain alkynyl groups. In certainembodiments, a straight chain or branched chain alkynyl group has twelveor fewer carbon atoms in its backbone (e.g., C₂₋₁₂ for straight chain;C₃₋₁₂ for branched chain). The term C₂₋₆ includes alkynyl groupscontaining 2 to 12 carbon atoms.

The term “alkylene” by itself or as part of another molecule means adivalent radical derived from a linear or branched alkane, asexemplified by (—CH₂-)_(n), wherein n may be 1 to 24 (e.g., 1 to 20, 1to 18, 1 to 16, 1 to 15, 1 to 12, 1 to 10, 1 to 8, 1 to 6, 1 to 5, 1 to4, 1 to 3, 1 to 2, 2 to 24, 2 to 12, 2 to 8). By way of example only,such groups include, but are not limited to, groups having 10 or fewercarbon atoms such as the structures —CH₂CH₂— and —CH₂CH₂CH₂CH₂—. A“lower alkyl” or “lower alkylene” is a shorter chain alkyl or alkylenegroup, generally having eight or fewer carbon atoms.

The term “alkoxy” is used in its conventional sense, and refers to alkylgroups linked to molecules via an oxygen atom. In some embodiments, analkoxy has twelve or fewer carbon atoms in its backbone (e.g., a C₁₋₁₂alkoxy). For example, C₁₋₁₀, C₁₋₈, C₁₋₆, CM, C₁₋₃, C₁₋₂). Non-limitingexamples of an alkoxy group include methoxy, ethoxy, propoxy, butoxy,and hexoxy.

The term “alkyleneoxyalkylene,” as used herein, refers to a divalentradical derived from a linear or branched alkyloxyalkane, asexemplified, but not limited by, —CH₂—CH₂—O—CH₂—CH₂— and —CH₂—CH₂—O—. Byway of example only, such groups include, but are not limited to, groupshaving the formula —(CH₂)_(n)—O—(CH₂)_(m)—, wherein n is an integer from1 to 50 (e.g., 1 to 40, 1 to 30, 1 to 25, 1 to 20, 1 to 18, 1 to 15, 1to 12, 1 to 10, 1 to 6, 1 to 6, 1 to 2, 1 to 3, 1 to 4, 2 to 50, 5 to50, 10 to 50, 15 to 50, 25 to 50, 5 to 15, 2 to 12, 20 to 30, and 6 to18) and m is an integer from 0 to 50 (e.g., 1 to 40, 1 to 30, 1 to 25, 1to 20, 1 to 18, 1 to 15, 1 to 12, 1 to 10, 1 to 6, 1 to 2, 1 to 3, 1 to4, 2 to 50, 5 to 50, 10 to 50, 15 to 50, 25 to 50, 5 to 15, 2 to 12, 20to 30, and 6 to 18).

The term “oligomeric alkyleneoxyalkylene” refers to p-repetitivealkyleneoxyalkylene wherein p is an integer of between 2 and 24 (e.g., 2to 20, 2 to 18, 2 to 16, 2 to 15, 2 to 12, 2 to 10, 2 to 8, 2 to 6, 2 to5, 2 to 4, 2 to 3). By way of example only, such groups include, but arenot limited to, groups having the formula —((CH₂)_(n)—O—(CH₂)_(m))_(p)—,wherein n is an integer from 1 to 50 (e.g., 1 to 40, 1 to 30, 1 to 25, 1to 20, 1 to 18, 1 to 15, 1 to 12, 1 to 10, 1 to 6, 1 to 6, 1 to 2, 1 to3, 1 to 4, 2 to 50, 5 to 50, 10 to 50, 15 to 50, 25 to 50, 5 to 15, 2 to12, 20 to 30, and 6 to 18), m is an integer from 0 to 50 (e.g., 1 to 40,1 to 30, 1 to 25, 1 to 20, 1 to 18, 1 to 15, 1 to 12, 1 to 10, 1 to 6, 1to 2, 1 to 3, 1 to 4, 2 to 50, 5 to 50, 10 to 50, 15 to 50, 25 to 50, 5to 15, 2 to 12, 20 to 30, and 6 to 18), and each p is independently aninteger from 1 to 10 (e.g., 1 to 8, 1 to 6, 1 to 5, 1 to 3, 2 to 10, 4to 10, 6 to 10, 2 to 8, and 3 to 6).

In general, the term “arylene” by itself or as part of another moleculemeans a divalent radical derived from an aryl, including, for example,5- and 6-membered single-ring aromatic groups, such as benzene andphenyl. Furthermore, the term “arylene” includes a divalent radicalderived from a multicyclic aryl group, e.g., tricyclic, bicyclic, suchas naphthalene and anthracene.

The term “substituted” means that an atom or group of atoms replaceshydrogen as a “substituent” attached to another group. For aryl andheteroaryl groups, the term “substituted”, unless otherwise indicated,refers to any level of substitution, namely mono, di, tri, tetra, orpenta substitution, where such substitution is permitted. Thesubstituents are independently selected, and substitution may be at anychemically accessible position. In some cases, two sites of substitutionmay come together to form a 3-10 membered cycloalkyl or heterocycloalkylring.

Substituents include, but are not limited to, halo, C₁-C₁₀ alkyl, C₂-C₁₀alkenyl, C₂-C₁₀ alkynyl, C₁-C₁₀ alkoxy, C₅-C₁₂ aralkyl, C₃-C₁₂cycloalkyl, C₄-C₁₂ cycloalkenyl, phenyl, substituted phenyl, toluoyl,xylenyl, biphenyl, C₂-C₁₂ alkoxyalkyl, C₅-C₁₂ alkoxyaryl, C₅-C₁₂aryloxyalkyl, C₇-C₁₂ oxyaryl, C₁-C₆ alkylsulfinyl, C₁-C₁₀ alkylsulfonyl,—(CH₂)_(m)—O—(C₁-C₁₀ alkyl) wherein m is from 1 to 8, aryl, substitutedaryl, substituted alkoxy, fluoroalkyl, heterocyclic radical, substitutedheterocyclic radical, nitroalkyl, —NO₂, —CN, —NR⁹C(O)—(C₁-C₁₀ alkyl),—C(O)—(C₁-C₁₀ alkyl), C₂-C₁₀ alkthioalkyl, —C(O)O—(C₁-C₁₀ alkyl), —OH,—SO₂, ═S, —COOH, —NR⁹ ₂, carbonyl, —C(O)—(C₁-C₁₀ alkyl)-CF₃, —C(O)—CF₃,—C(O)NR⁹ ₂, —(C₁-C₁₀ aryl)-S—(C₆-C₁₀ aryl), —C(O)—(C₆-C₁₀ aryl),—(CH₂)_(m)—O—(CH₂)_(m)—O—(C₁-C₁₀ alkyl) wherein each m is from 1 to 8,—C(O)NR⁹ ₂, —C(S)NR⁹ ₂, —SO₂NR⁹ ₂, —NR⁹C(O)NR⁹ ₂, —NR⁹C(S)NR⁹ ₂, saltsthereof, and the like. Each R⁹ group in the preceding list independentlyincludes, but is not limited to, H, alkyl or substituted alkyl, aryl orsubstituted aryl, or alkylaryl. Where substituent groups are specifiedby their conventional chemical formulas, written from left to right,they equally encompass the chemically identical substituents that wouldresult from writing the structure from right to left, for example,—CH₂O— is equivalent to —OCH₂—.

The term “polymer backbone” refers to the main chain of a linear orbranched polymer.

The term “water-soluble polymer backbone” refers to a polymer backbonehaving water-solubility or dispersibility in water at ambienttemperatures and a pH of about 7. For instance, a polyethylene glycolbackbone is considered to be water-soluble if the correspondingpolyethylene glycol can be solubilized or dispersed in water at ambienttemperatures and a pH of about 7.

The term “nucleotidic polymer” refers to a single- or double-strandedpolymer chain composed of two or more nucleic acids. The term “nucleicacid” refers to deoxyribonucleotides or ribonucleotides. By way ofexample only, such nucleic acids and nucleic acid polymers include, butare not limited to, (i) analogues of natural nucleotides which havesimilar binding properties as a reference nucleic acid and aremetabolized in a manner similar to naturally occurring nucleotides; (ii)oligonucleotide analogs including, but are not limited to, PNA(peptidonucleic acid), analogs of DNA used in antisense technology(phosphorothioates, phosphoroamidites, and the like); (iii)conservatively modified variants thereof (including but not limited to,degenerate codon substitutions) and complementary sequences.

The term “peptidic polymer” refers to a polymer of two or more aminoacid residues. The term applies to naturally occurring amino acidpolymers as well as amino acid polymers in which one or more amino acidresidues is a non-natural amino acid.

As used herein, a “biologically active molecule” includes any moleculewhich can have a biological effect. Examples of biologically activemolecules include therapeutic agents, small molecules, oligo- andpolypeptides, oligonucleotides, coding DNA sequences, antisense DNAsequences, mRNAs, antisense RNA sequences, RNAis, and siRNAs,carbohydrates, lipids, growth factors, enzymes, transcription factors,toxins, antigenic peptides (as for vaccines), antibodies, and antibodyfragments.

The term “group reactive with a biologically active molecule” refers toa functional group that can be covalently bound to a functional group ofa biologically active molecule.

The terms “protecting group” and “protective group” refer to a moietythat reversibly chemically modifies a functional group in order toobtain chemoselectivity or in order to reduce degradation in one or moresubsequent chemical reactions. Suitable protecting groups are well knownin the art (see, e.g., Greene and Wuts, Protective Groups in OrganicSynthesis, 3rd Ed., John Wiley & Sons, New York, N.Y., 1999, which isincorporated herein by reference in its entirety).

The term “detectable functional group” refers a functional group thatphysically or chemically interacts with its environment to produce asignal or product that can be detected by analytical and/or imagingmethods such as visible, UV-, IR-, NIR-light, X-Ray, and NMR-basedimaging methods, enzymatic assays, and UV-, IR-, NMR-, X-ray-, and massspectrometry-based analytics.

As used herein, a “fluorophore” is a chemical group that can be excitedby light to emit fluorescence. Some suitable fluorophores may be excitedby light to emit phosphorescence. As used herein, a “dye” may include afluorophore. Non-limiting examples of a fluorophore include: 1,5IAEDANS; 1,8-ANS; 4-Methylumbelliferone;5-carboxy-2,7-dichlorofluorescein; 5-Carboxyfluorescein (5-FAM);5-Carboxytetramethylrhodamine (5-TAMRA); 5-FAM (5-Carboxyfluorescein);5-HAT (Hydroxy Tryptamine); 5-Hydroxy Tryptamine (HAT); 5-ROX(carboxy-X-rhodamine); 5-TAMIA (5-Carboxytetranethylrhodamine);6-Carboxyrhodamine 6G; 6-CR 6G; 6-JOE; 7-Amino-4-methylcoumarin;7-Aminoactinomycin D (7-AAD); 7-Hydroxy-4-methylcoumarin;9-Amino-6-chloro-2-methoxyacridine; ABQ; Acid Fuchsin; ACMA(9-Amino-6-chloro-2-methoxyacridine); Acridine Orange; Acridine Red;Acridine Yellow; Acriflavin; Acriflavin Feulgen SITSA; Alexa Fluor 350™;Alexa Fluor 430™; Alexa Fluor 488™; Alexa Fluor 532™; Alexa Fluor 546™;Alexa Fluor 568™; Alexa Fluor 594™; Alexa Fluor 633™; Alexa Fluor 647™;Alexa Fluor 660™; Alexa Fluor 680™; Alizarin Complexon; Alizarin Red;Allophycocyanin (APC); AMC; AMCA-S; AMCA (Aminomethylcoumarin); AMCA-X;Aminoactinomycin D; Aminocoumarin; Aminomethylcoumarin (AMCA); AnilinBlue; Anthrocyl stearate; APC (Allophycocyanin); APC-Cy7; APTS; AstrazonBrilliant Red 4G; Astrazon Orange R; Astrazon Red 6B; Astrazon Yellow 7GLL; Atabrine; ATTO-TAG™ CBQCA; ATTO-TAG™ FQ; Auramine; Aurophosphine G;Aurophosphine; BAO 9 (Bisaminophenyloxadiazole); Berberine Sulphate;Beta Lactamase; BFP blue shifted GFP (Y66H); Blue Fluorescent Protein;BFP/GFP FRET; Bimane; Bisbenzamide; Bisbenzimide (Hoechst); BlancophorFFG; Blancophor SV; BOBO™-1; BOBO™-3; Bodipy 492/515; Bodipy 493/503;Bodipy 500/510; Bodipy 505/515; Bodipy 530/550; Bodipy 542/563; Bodipy558/568; Bodipy 564/570; Bodipy 576/589; Bodipy 581/591; Bodipy630/650-X; Bodipy 650/665-X; Bodipy 665/676; Bodipy FL; Bodipy FL ATP;Bodipy Fl-Ceramide; Bodipy R6G SE; Bodipy TMR; Bodipy TMR-X conjugate;Bodipy TMR-X, SE; Bodipy TR; Bodipy TR ATP; Bodipy TR-X SE; BO-PRO™-1;BO-PRO™-3; Brilliant Sulphoflavin FF; Calcein; Calcein Blue; CalciumCrimson™; Calcium Green; Calcium Orange; Calcofluor White;Carboxy-X-rhodamine (5-ROX); Cascade Blue™; Cascade Yellow;Catecholamine; CCF2 (GeneBlazer); CFDA; CFP-Cyan Fluorescent Protein;CFP/YFP FRET; Chlorophyll; Chromomycin A; CL-NERF (Ratio Dye, pH);CMFDA; Coelenterazine f; Coelenterazine fcp; Coelenterazine h;Coelenterazine hep; Coelenterazine ip; Coelenterazine n; CoelenterazineO; Coumarin Phalloidin; C-phycocyanine; CPM Methylcoumarin; CTC; CTCFormazan; Cy2™; Cy3.1 8; Cy3.5™; Cy3™; Cy5.1 8; Cy5.5™; Cy5™; Cy7™; CyanGFP; cyclic AMP Fluorosensor (FiCRhR); Dabcyl; Dansyl; Dansyl Amine;Dansyl Cadaverine; Dansyl Chloride; Dansyl DHPE; Dansyl fluoride; DAPI;Dapoxyl; Dapoxyl 2; Dapoxyl 3; DCFDA; DCFH (DichlorodihydrofluoresceinDiacetate); DDAO; DHR (Dihydorhodamine 123); Di-4-ANEPPS; Di-8-ANEPPS(non-ratio); DiA (4-Di-16-ASP); Dichlorodihydrofluorescein Diacetate(DCFH); DiD-Lipophilic Tracer; DiD (DiIC18(5)); DIDS; Dihydorhodamine123 (DHR); DiI (DiIC18(3)); Dinitrophenol; DiO (DiOC18(3)); DiR; DiR(DiIC18(7)); DNP; Dopamine; DsRed; DTAF; DY-630-NHS; DY-635-NHS; EBFP;ECFP; EGFP; ELF 97; Eosin; Erythrosin; Erythrosin ITC; Ethidium Bromide;Ethidium homodimer-1 (EthD-1); Euchrysin; EukoLight; Europium (III)chloride; EYFP; Fast Blue; FDA; Feulgen (Pararosaniline); FITC; FlazoOrange; Fluo-3; Fluo-4; Fluorescein (FITC); Fluorescein Diacetate;Fluoro-Emerald; Fluoro-Gold (Hydroxystilbamidine); Fluor-Ruby; FluorX;FM 1-43™; FM 4-46; Fura Red™; Fura Red™/Fluo-3; Fura-2; Fura-2/BCECF;Genacryl Brilliant Red B; Genacryl Brilliant Yellow 1OGF; Genacryl Pink3G; Genacryl Yellow 5GF; GeneBlazer (CCF2); GFP (S65T); GFP red shifted(rsGFP); GFP wild type, non-UV excitation (wtGFP); GFP wild type, WVexcitation (wtGFP); GFPuv; Gloxalic Acid; Granular Blue;Haematoporphyrin; Hoechst 33258; Hoechst 33342; Hoechst 34580; HPTS;Hydroxycoumarin; Hydroxystilbamidine (FluoroGold); Hydroxytryptamine;Indo-1; Indodicarbocyanine (DiD); Indotricarbocyanine (DiR); IntrawhiteCf; JC-1; JO-JO-1; JO-PRO-1; Laurodan; LDS 751 (DNA); LDS 751 (RNA);Leucophor PAF; Leucophor SF; Leucophor WS; Lissamine Rhodamine;Lissamine Rhodamine B; Calcein/Ethidium homodimer; LOLO-1; LO-PRO-1;Lucifer Yellow; Lyso Tracker Blue; Lyso Tracker Blue-White; Lyso TrackerGreen; Lyso Tracker Red; Lyso Tracker Yellow; LysoSensor Blue;LysoSensor Green; LysoSensor Yellow/Blue; Mag Green; Magdala Red(Phloxin B); Mag-Fura Red; Mag-Fura-2; Mag-Fura-5; Mag-Indo-1; MagnesiumGreen; Magnesium Orange; Malachite Green; Marina Blue; Maxilon BrilliantFlavin 10 GFF; Maxilon Brilliant Flavin 8 GFF; Merocyanin;Methoxycoumarin; Mitotracker Green FM; Mitotracker Orange; MitotrackerRed; Mitramycin; Monobromobimane; Monobromobimane (mBBr-GSH);Monochlorobimane; MPS (Methyl Green Pyronine Stilbene); NBD; NBD Amine;Nile Red; Nitrobenzoxadidole; Noradrenaline; Nuclear Fast Red; NuclearYellow; Nylosan Brilliant Iavin E8G; Oregon Green; Oregon Green 488-X;Oregon Green™; Oregon Green™ 488; Oregon Green™ 500; Oregon Green™ 514;Pacific Blue; Pararosaniline (Feulgen); PBFI; PE-Cy5; PE-Cy7; PerCP;PerCP-Cy5.5; PE-TexasRed [Red 613]; Phloxin B (Magdala Red); PhorwiteAR; Phorwite BKL; Phorwite Rev; Phorwite RPA; Phosphine 3R;Phycoerythrin B [PE]; Phycoerythrin R [PE]; PKH26 (Sigma); PKH67; PMIA;Pontochrome Blue Black; POPO-1; POPO-3; PO-PRO-1; PO-PRO-3; Primuline;Procion Yellow; Propidium Iodid (PI); PyMPO; Pyrene; Pyronine; PyronineB; Pyrozal Brilliant Flavin 7GF; QSY 7; Quinacrine Mustard; Red 613[PE-TexasRed]; Resorufin; RH 414; Rhod-2; Rhodamine; Rhodamine 110;Rhodamine 123; Rhodamine 5 GLD; Rhodamine 6G; Rhodamine B; Rhodamine B200; Rhodamine B extra; Rhodamine BB; Rhodamine BG; Rhodamine Green;Rhodamine Phallicidine; Rhodamine Phalloidine; Rhodamine Red; RhodamineWT; Rose Bengal; R-phycocyanine; R-phycoerythrin (PE); RsGFP; S65A;S65C; S65L; S65T; Sapphire GFP; SBFI; Serotonin; Sevron Brilliant Red2B; Sevron Brilliant Red 4G; Sevron Brilliant Red B; Sevron Orange;Sevron Yellow L; sgBFP™; sgBFP™ (super glow BFP); sgGFP™; sgGFP™ (superglow GFP); SITS; SITS (Primuline); SITS (Stilbene IsothiosulphonicAcid); SNAFL calcein; SNAFL-1; SNAFL-2; SNARF calcein; SNARFI; SodiumGreen; SpectrumAqua; SpectrumGreen; SpectrumOrange; Spectrum Red; SPQ(6-methoxy-N-(3-sulfopropyl)quinolinium); Stilbene; Sulphorhodamine Bcan C; Sulphorhodamine G Extra; SYTO 11; SYTO 12; SYTO 13; SYTO 14; SYTO15; SYTO 16; SYTO 17; SYTO 18; SYTO 20; SYTO 21; SYTO 22; SYTO 23; SYTO24; SYTO 25; SYTO 40; SYTO 41; SYTO 42; SYTO 43; SYTO 44; SYTO 45; SYTO59; SYTO 60; SYTO 61; SYTO 62; SYTO 63; SYTO 64; SYTO 80; SYTO 81; SYTO82; SYTO 83; SYTO 84; SYTO 85; SYTOXBlue; SYTOX Green; SYTOX Orange;Tetracycline; Tetramethylrhodamine (TRITC); Texas Red™; Texas Red-X™conjugate; Thiadicarbocyanine (DiSC3); Thiazine Red R; Thiazole Orange;Thioflavin 5; Thioflavin S; Thioflavin TCN; Thiolyte; Thiozole Orange;Tinopol CBS (Calcofluor White); TMR; TO-PRO-1; TO-PRO-3; TO-PRO-5;TOTO-1; TOTO-3; Tricolor (PE-Cy5); TRITCTetramethylRodaminelsoThioCyanate; True Blue; TruRed; Ultralite; UranineB; Uvitex SFC; wt GFP; WW 781; X-Rhodamine; XRITC; Xylene Orange; Y66F;Y66H; Y66W; Yellow GFP; YFP; YO-PRO-1; YO-PRO-3; YOYO-1; and YOYO-3. Asused herein, a “fluorophore” may include a salt of the fluorophore.

Fluorophores may include derivatives that have been modified tofacilitate conjugation to another reactive molecule. As such,fluorophores may include amine-reactive derivatives such asisothiocyanate derivatives and/or succinimidyl ester derivatives of thefluorophore.

The term “hydrophobic separation handle” refers to a moiety that whenattached to or part of a compound reduces the hydrophilicity of thatcompound, i.e. reduces its tendency to be solved or dispersed in water.The term “separation handle” refers to a moiety that when attached to orpart of a compound alters the mobility of that compound in achromatographic method such that its separation from contaminants isimproved. Alternatively, the term “separation handle” refers to a moietythat when attached to or part of a compound improves the yield of thecompound in a chromatographic method in comparison to a hydrogensubstituent.

The term “hydrophobicity” refers to the relative degree with which acompound or moiety is solved or dispersed in a non-aqueous solvent suchas n-octanol. The degree of hydrophobicity or hydrophilicity of acompound or moiety can be measured using methods known in the art, suchas, reversed phase chromatography and other chromatographic methods,partitioning, accessible surface area methods, and measurement ofphysical properties such as partial molar heat capacity, transitiontemperature and surface tension.

The term “activating group” refers to a moiety that increases thecapability of the group reactive with a biologically active molecule toform a covalent bond with a biologically active molecule. Usually thesegroups increase or decrease the electronegativity of a selected moietyso it becomes more nucleophilic or more electrophilic. Non-limitingexamples of an activating group include: lower alkylamino,diloweralkylamino, amino, halo, aryl, lower alkoxy, lower aralkoxy,aryloxy, mercapto, lower alkylthio, nitro, monophaloalkyl, dihaloalkyl,trihaloalkyl (e.g., CF₃), halo, formyl, lower alkanoyl, loweralkylsulfonyl, lower alkylsulfinyl, and the like.

The term “essentially pure” refers to chemical purity of a compoundprovided herein that may be substantially or essentially free of othercomponents which normally accompany or interact with the compound priorto purification. By way of example only, a compound may be “essentiallypure” when the preparation of the compound contains less than about 30%,less than about 25%, less than about 20%, less than about 15%, less thanabout 10%, less than about 5%, less than about 4%, less than about 3%,less than about 2%, or less than about 1% (by dry weight) ofcontaminating components. Thus, an “essentially pure” compound may havea purity level of about 70%, about 75%, about 80%, about 85%, about 90%,about 95%, about 96%, about 97%, about 98%, about 99% or greater. Forthe purposes of this document, preparations of functionalized polymersor conjugates differing only in the length of their polymer chain areconsidered to be essentially pure. By way of example a preparation of amono-functionalized compound may be “essentially pure” when thepreparation contains less than about 30%, less than about 25%, less thanabout 20%, less than about 15%, less than about 10%, less than about 5%,less than about 4%, less than about 3%, less than about 2%, or less thanabout 1% (by dry weight) of contaminating unfunctionalized and/orpoly-functionalized polymers. An essentially pure compound may beobtained using chromatographic purification methods.

The term “protic solvent” is used herein to refer to solvents whichcomprise dissociable hydrogen ions. Examples of protic solvents includealcohols, such as ethanol, and methanol.

The phrase “pharmaceutically acceptable” is used herein to refer tothose inhibitors, materials, compositions, and/or dosage forms whichare, within the scope of sound medical judgment, suitable for use incontact with the tissues of human beings and animals without excessivetoxicity, irritation, allergic response, or other problem orcomplication, commensurate with a reasonable benefit/risk ratio.

Some of the compounds provided herein are acidic and may form a saltwith a pharmaceutically acceptable cation. Some of the compounds hereincan be basic and accordingly, may form a salt with a pharmaceuticallyacceptable anion. All such salts, including di-salts are within thescope of the compositions described herein and they can be prepared byconventional methods. For example, salts can be prepared by contactingthe acidic and basic entities, in either an aqueous, non-aqueous orpartially aqueous medium. The salts are recovered by using at least oneof the following techniques: filtration, precipitation with anon-solvent followed by filtration, evaporation of the solvent, or, inthe case of aqueous solutions, lyophilization.

Salts, for example, include: (1) acid addition salts, formed withinorganic acids such as hydrochloric acid, hydrobromic acid, sulfuricacid, nitric acid, phosphoric acid, and the like; or formed with organicacids such as acetic acid, propionic acid, hexanoic acid,cyclopentanepropionic acid, glycolic acid, pyruvic acid, lactic acid,malonic acid, succinic acid, malic acid, maleic acid, fumaric acid,tartaric acid, citric acid, benzoic acid, 3-(4-hydroxybenzoyl)benzoicacid, cinnamic acid, mandelic acid, methanesulfonic acid, ethanesulfonicacid, 1,2-ethanedisulfonic acid, 2-hydroxyethanesulfonic acid,benzenesulfonic acid, 2-naphthalenesulfonic acid,4-methylbicyclo-[2.2.2]oct-2-ene-1-carboxylic acid, glucoheptonic acid,4,4′-methylenebis-(3-hydroxy-2-ene-1-carboxylic acid), 3-phenylpropionicacid, trimethylacetic acid, tertiary butylacetic acid, lauryl sulfuricacid, gluconic acid, glutamic acid, hydroxynaphthoic acid, salicylicacid, stearic acid, muconic acid, and the like; and (2) salts formedwhen an acidic proton present in the parent compound either is replacedby a metal ion, e.g., an alkali metal ion, an alkaline earth ion, or analuminum ion; or coordinates with an organic base. Acceptable organicbases include ethanolamine, diethanolamine, triethanolamine,tromethamine, N-methylglucamine, and the like. Acceptable inorganicbases include aluminum hydroxide, calcium hydroxide, potassiumhydroxide, sodium carbonate, sodium hydroxide, and the like.

Compounds Compounds of Formula (I)

Provided herein is a compound comprising a water-soluble,non-nucleotidic and non-peptidic polymer backbone having at least oneterminus covalently bonded to a structure of formula (1):

or pharmaceutical salt thereof wherein: A is the point of bonding to aterminus of the polymer backbone, E is an oxygen or sulfur atom, K isselected from the group consisting of alkylene, alkyleneoxyalkylene, oran oligomeric form of alkyleneoxyalkylene, G is selected from the groupconsisting of hydrogen, an alkoxy, or a hydrophobic separation handle,Z¹ and Z² can be oxygen or nitrogen, in such way that both Z¹ and Z² maybe oxygen, but when Z¹ is NH then Z² is oxygen, and when Z² is NH thenZ¹ is oxygen, L is selected from the group consisting of a divalentradical of a nucleoside, linear alkylene, branched alkylene,alkyleneoxyalkylene, oligomeric form of alkyleneoxyalkylene, arylene,and substituted arylene, M is a protected group that when deprotected isreactive with a biologically active molecule, a group reactive with abiologically active molecule, or detectable functional group, R is aprotecting group, activating group, hydrogen or absent.

A polymer backbone, as provided herein, can be branched or linear. Forexample, a polymer backbone can have from 2 to 100 termini (e.g., 2 to80, 2 to 75, 2 to 60, 2 to 50, 2 to 40, 2 to 35, 2 to 25, 2 to 10, 2 to5, 4 to 20, 5 to 25, 10 to 50, 25 to 75, 3 to 6, 5 to 15 termini). Insome embodiments, a polymer is linear and therefore has 2 termini. Insome embodiments, only one termini of a polymer backbone is covalentlybonded to the structure of formula (1). In some embodiments, wherein apolymer has two termini, both termini of the polymer backbone arecovalently bonded to the structure of formula (1).

A polymer backbone can be, for example, poly(alkylene glycol),poly(oxyethylated polyol), poly(olefinic alcohol), poly(α-hydroxy acid),poly(vinyl alcohol), polyoxazoline, or a copolymer thereof. Apolyalkylene glycol includes linear or branched polymeric polyetherpolyols. Such polyalkylene glycols, include, but are not limited to,polyethylene glycol, polypropylene glycol, polybutylene glycol, andderivatives thereof. Other exemplary embodiments are listed, forexample, in commercial supplier catalogs, such as ShearwaterCorporation's catalog “Polyethylene Glycol and Derivatives forBiomedical Applications” (2001). By way of example only, such polymericpolyether polyols have average molecular weights between about 0.1 kDato about 100 kDa. By way of example, such polymeric poly ether polyolsinclude, but are not limited to, between about 500 Da and about 100,000Da or more. The molecular weight of the polymer may be between about 500Da and about 100,000 Da. For example, a polymer used herein can have amolecular weight of about 100,000 Da, 95,000 Da, 90,000 Da, 85,000 Da,80,000 Da, 75,000 Da, 70,000 Da, 65,000 Da, 60,000 Da, 55,000 Da, 50,000Da, 45,000 Da, 40,000 Da, 35,000 Da, 30,000 Da, 25,000 Da, 20.000 Da,15,000 Da, 10,000 Da, 9,000 Da, 8,000 Da, 7,000 Da, 6,000 Da, 5,000 Da,4.000 Da, 3,000 Da, 2,000 Da, 1,000 Da, 900 Da, 800 Da, 700 Da, 600 Da,and 500 Da. In some embodiments, the molecular weight of the polymer isbetween about 500 Da and about 50,000 Da. In some embodiments, themolecular weight of the polymer is between about 500 Da and about 40,000Da. In some embodiments, the molecular weight of the polymer is betweenabout 1,000 Da and about 40,000 Da. In some embodiments, the molecularweight of the polymer is between about 5,000 Da and about 40,000 Da. Insome embodiments, the molecular weight of the polymer is between about10,000 Da and about 40,000 Da.

In some embodiments, a polymer backbone is a linear or branchedpoly(ethylene glycol).

In some embodiments, the polyethylene glycol) molecule is a linearpolymer. The molecular weight of the linear chain PEG may be betweenabout 1,000 Da and about 100.000 Da. For example, a linear chain PEGused herein can have a molecular weight of about 100,000 Da, 95,000 Da,90,000 Da, 85,000 Da, 80,000 Da, 75,000 Da, 70,000 Da, 65,000 Da, 60,000Da, 55,000 Da, 50,000 Da, 45,000 Da, 40,000 Da, 35,000 Da, 30.000 Da,25,000 Da, 20,000 Da, 15,000 Da, 10,000 Da, 9,000 Da, 8,000 Da, 7,000Da, 6.000 Da, 5,000 Da, 4,000 Da, 3,000 Da, 2,000 Da, and 1,000 Da. Insome embodiments, the molecular weight of the linear chain PEG isbetween about 1,000 Da and about 50,000 Da. In some embodiments, themolecular weight of the linear chain PEG is between about 1,000 Da andabout 40,000 Da. In some embodiments, the molecular weight of the linearchain PEG is between about 5,000 Da and about 40,000 Da. In someembodiments, the molecular weight of the linear chain PEG is betweenabout 5,000 Da and about 20,000 Da.

In some embodiments, the polyethylene glycol) molecule is a branchedpolymer. The molecular weight of the branched chain PEG may be betweenabout 1,000 Da and about 100,000 Da. For example, a branched chain PEGused herein can have a molecular weight of about 100,000 Da, 95,000 Da,90,000 Da, 85,000 Da, 80,000 Da, 75,000 Da, 70.000 Da, 65,000 Da, 60,000Da, 55,000 Da, 50,000 Da, 45,000 Da, 40,000 Da, 35,000 Da, 30,000 Da,25,000 Da, 20,000 Da, 15,000 Da, 10,000 Da, 9,000 Da, 8,000 Da, 7,000Da, 6,000 Da, 5,000 Da, 4,000 Da, 3,000 Da, 2,000 Da, and 1,000 Da. Insome embodiments, the molecular weight of the branched chain PEG isbetween about 1,000 Da and about 50,000 Da. In some embodiments, themolecular weight of the branched chain PEG is between about 1,000 Da andabout 40,000 Da. In some embodiments, the molecular weight of thebranched chain PEG is between about 5,000 Da and about 40,000 Da. Insome embodiments, the molecular weight of the branched chain PEG isbetween about 5,000 Da and about 20,000 Da.

In some embodiments, E is oxygen. In some embodiments, E is sulfur.

In some embodiments, K is a linear or branched alkylene. For example, Kcan be selected from the group consisting of: methylene, ethylene,propylene, isopropylene, butylene, isobutylene, sec-butylene,tert-butylene, and hexylene. In some embodiments, K can be analkyleneoxyalkylene or an oligomeric alkyleneoxyalkylene. For example, Kcan be a residue from diethylene glycol, triethylene glycol,tetraethylene glycol, or hexaethylene glycol. In some embodiments, K isselected from the group consisting of —(CH₂)_(n)— and—((CH₂)_(n)—O—(CH₂)_(m))_(p)—, wherein n is an integer from 1 to 50(e.g., 1 to 40, 1 to 30, 1 to 25, 1 to 20, 1 to 18, 1 to 15, 1 to 12, 1to 10, 1 to 6, 1 to 6, 1 to 2, 1 to 3, 1 to 4, 2 to 50, 5 to 50, 10 to50, 15 to 50, 25 to 50, 5 to 15, 2 to 12, 20 to 30, and 6 to 18), m isan integer from 0 to 50 (e.g., 1 to 40, 1 to 30, 1 to 25, 1 to 20, 1 to18, 1 to 15, 1 to 12, 1 to 10, 1 to 6, 1 to 2, 1 to 3, 1 to 4, 2 to 50,5 to 50, 10 to 50, 15 to 50, 25 to 50, 5 to 15, 2 to 12, 20 to 30, and 6to 18), and each p is independently an integer from 1 to 10 (e.g., 1 to8, 1 to 6, 1 to 5, 1 to 3, 2 to 10, 4 to 10, 6 to 10, 2 to 8, and 3 to6).

In some embodiments, G is a hydrophobic separation handle. For example,G can be a substituted or unsubstituted trityloxy group. In someembodiments, G is selected from the group consisting of monoalkoxysubstituted trityloxy group or dialkoxy substituted trityloxy group.

In some embodiments, one of Z¹ and Z² is NH and the other is O. Forexample, Z¹ is O and Z² is NH; Z¹ is NH and Z² is O. In someembodiments, both Z¹ and Z² are O.

In some embodiments, L is a linear or branched alkylene. For example, Lcan be selected from the group consisting of: methylene, ethylene,propylene, isopropylene, butylene, isobutylene, sec-butylene,tert-butylene, and hexylene. In some embodiments, L can be analkyleneoxyalkylene or an oligomeric alkyleneoxyalkylene. For example, Lcan be a residue from diethylene glycol, triethylene glycol,tetraethylene glycol or hexaethylene glycol. In some embodiments, L isselected from the group consisting of —(CH₂)_(n)— and—((CH₂)_(n)—O—(CH₂)_(m))_(p)—, wherein n is an integer from 1 to 50(e.g., 1 to 40, 1 to 30, 1 to 25, 1 to 20, 1 to 18, 1 to 15, 1 to 12, 1to 10, 1 to 6, 1 to 6, 1 to 2, 1 to 3, 1 to 4, 2 to 50, 5 to 50, 10 to50, 15 to 50, 25 to 50, 5 to 15, 2 to 12, 20 to 30, and 6 to 18), m isan integer from 0 to 50 (e.g., 1 to 40, 1 to 30, 1 to 25, 1 to 20, 1 to18, 1 to 15, 1 to 12, 1 to 10, 1 to 6, 1 to 2, 1 to 3, 1 to 4, 2 to 50,5 to 50, 10 to 50, 15 to 50, 25 to 50, 5 to 15, 2 to 12, 20 to 30, and 6to 18), and each p is independently an integer from 1 to 10 (e.g., 1 to8, 1 to 6, 1 to 5, 1 to 3, 2 to 10, 4 to 10, 6 to 10, 2 to 8, and 3 to6).

In some embodiments, L is a substituted or unsubstituted arylene. Forexample, L can be a structure with the formula:

where W is a substituent and r is an integer from 0 to 4. For example, Wcan be selected from the group consisting of: halo, C₁-C₁₀ alkyl, C₂-C₁₀alkenyl, C₂-C₁₀ alkynyl, C₁-C₁₀ alkoxy, C₅-C₁₂ aralkyl, C₃-C₁₂cycloalkyl, C₄-C₁₂ cycloalkenyl, phenyl, substituted phenyl, toluoyl,xylenyl, biphenyl, C₂-C₁₂ alkoxyalkyl, C₅-C₁₂ alkoxyaryl, C₅-C₁₂aryloxyalkyl, C₇-C₁₂ oxyaryl, C₁-C₆ alkylsulfinyl, C₁-C₁₀ alkylsulfonyl,—(CH₂)_(m)—O—(C₁-C₁₀ alkyl) wherein m is from 1 to 8, aryl, substitutedaryl, substituted alkoxy, fluoroalkyl, heterocyclic radical, substitutedheterocyclic radical, nitroalkyl, —NO₂, —CN, —NR⁹C(O)—(C₁-C₁₀ alkyl),—C(O)—(C₁-C₁₀ alkyl), C₂-C₁₀ alkthioalkyl, —C(O)O—(C₁-C₁₀ alkyl), —OH,—SO₂, ═S, —COOH, —NR⁹ ₂, carbonyl, —C(O)—(C₁-C₁₀ alkyl)-CF₃, —C(O)—CF₃,—C(O)NR⁹ ₂, —(C₁-C₁₀ aryl)-S—(C₆-C₁₀ aryl), —C(O)—(C₆-C₁₀ aryl),—(CH₂)_(m)—O—(CH₂)_(m)—O—(C₁-C₁₀ alkyl) wherein each m is from 1 to 8,—C(O)NR⁹ ₂, —C(S)NR⁹ ₂, —SO₂NR⁹ ₂, —NR⁹C(O)NR⁹ ₂, —NR⁹C(S)NR⁹ ₂, saltsthereof, and the like. Each R⁹ group in the preceding list independentlyincludes, but is not limited to, H, alkyl or substituted alkyl, aryl orsubstituted aryl, or alkylaryl. In some embodiments, W is R¹ asdescribed above.

Non-limiting examples of L include:

In some cases, L can also be a divalent radical of a nucleoside. Forexample, L can be a divalent radical of a natural nucleoside, such asadenosine, deoxyadenosine, guanosine, deoxyguanosine, 5-methyluridine,thymidine, uridine, deoxyuridine, cytidine, and deoxycytidine.

A group reactive with a biologically active molecule can be selectedfrom the group consisting of: hydroxyl, amine, thiol, carboxyl,aldehyde, glyoxal, dione, alkenyl, alkynyl, alkedienyl, azide,acrylamide, vinyl sulfone, hydrazide, aminoxy, maleimide,dithiopyridine, iodoacetamide. In some embodiments, the group isprotected or further reacted with a group R as shown in the structure offormula (1). The point of attachment of such a group is well understoodby those of skill in the art.

In some embodiments, M is a detectable functional group. A detectablefunctional group, as used herein, can be any chemical or substance whichis used to provide a signal or contrast in imaging. The signal enhancingdomain can be an organic molecule, metal ion, salt or chelate, particle(particularly iron particle), or labeled peptide, protein, polymer orliposome. For example, a detectable functional group can include one ormore of a radionuclide, a paramagnetic metal, a fluorophore, a dye, andan enzyme substrate. In some embodiments, a detectable functional groupis biotin or a fluorophore.

In some embodiments, the detectable functional group is aphysiologically compatible metal chelate compound consisting of one ormore cyclic or acyclic organic chelating agents complexed to one or moremetal ions with atomic numbers 21-29, 42, 44, or 57-83.

For x-ray imaging, the detectable functional group may consist ofiodinated organic molecules or chelates of heavy metal ions of atomicnumbers 57 to 83. In some embodiments, the detectable functional groupis ¹²⁵I-IgG. Examples of suitable compounds are described in M. Sovak,ed., “Radiocontrast Agents,” Springer-Verlag. pp. 23-125 (1984) and U.S.Pat. No. 4,647,447.

For ultrasound imaging, the detectable functional group can consist ofgas-filled bubbles such as Albunex, Echovist, or Levovist, or particlesor metal chelates where the metal ions have atomic numbers 21-29, 42, 44or 57-83. Examples of suitable compounds are described in Tyler et al.,Ultrasonic Imaging. 3, pp. 323-29 (1981) and D. P. Swanson, “EnhancementAgents for Ultrasound: Fundamentals,” Pharmaceuticals in MedicalImaging, pp. 682-87. (1990).

For nuclear radiopharmaceutical imaging or radiotherapy, the detectablefunctional group can consist of a radioactive molecule. In someembodiments, the chelates of Tc, Re, Co, Cu, Au, Ag, Pb, Bi, In, and Gacan be used. In some embodiments, the chelates of Tc-99m can be used.Examples of suitable compounds are described in Rayudu GVS, Radiotracersfor Medical Applications, I, pp. 201 and D. P. Swanson et al., ed.,Pharmaceuticals in Medical Imaging, pp. 279-644 (1990).

For ultraviolet/visible/infrared light imaging, the detectablefunctional group can consist of any organic or inorganic dye or anymetal chelate.

For MRI, the detectable functional group can consist of a metal-ligandcomplex of a paramagnetic form of a metal ion with atomic numbers 21-29,42, 44, or 57-83. In some embodiments, the paramagnetic metal is chosenfrom: Gd(III), Fe(III), Mn(II and III), Cr(III), Cu(II), Dy(III),Tb(III), Ho(III), Er(III) and Eu(III). Many suitable chelating ligandsfor MRI agents are known in the art. These can also be used for metalchelates for other forms of biological imaging. For example, an imagingagent can include: Gadovist, Magnevist, Dotarem, Omniscan, and ProHance.

In some embodiments, R is absent. In some embodiments, R is a protectinggroup. For this purpose, R may include any suitable protecting groupbased on the group to be protected. For example, R may include anysuitable hydroxyl functional group including, but not limited to, ether,ester, carbonate, or sulfonate protecting groups.

In particular, the ether protecting group may include benzyloxymethyl(BOM), methylthiomethyl (MTM), phenylthiomethyl (PTM), cyanoethyl,2,2-dichloro-1,1-difluoroethyl, 2-chloroethyl, 2-bromoethyl,tetrahydropyranyl (THP), phenacyl, 4-bromophenacyl, allyl, propargyl,t-butyl benzyl, 2,6-dimethylbenzyl, 4-methoxybenzyl (MPM-OAr),o-nitrobenzyl, 2,6-dichlorobenzyl, 3,4-dichlorobenzyl,4-(dimethylamino)carbonylbenzyl, 4-methylsulfinylbenzyl (Msib),9-anthrylemethyl, 4-picolyl, heptafluoro-p-tolyl, tetrafluoro-4-pyridyl,trimethylsilyl (TMS), and protecting groups.

The ester protecting group may include acetoxy (OAc), aryl formate,acetate, levulinate, pivaloate, benzoate, and 9-fluoroenecarboxylate. Inone embodiment, the ester protecting group is an acetoxy group.

The carbonate protecting group may include aryl methyl carbonate,1-adamantyl carbonate (Adoc-OAr), t-butyl carbonate (BOC-OAr),4-methylsulfinylbenzyl carbonate (Msz-OAr), 2,4-dimethylpent-3-ylcarbonate (Doc-OAr), aryl 2,2,2-trichloroethyl carbonate.

The sulfonate protecting groups may include aryl methanesulfonate, aryltoluenesulfonate, and aryl 2-formylbenzenesulfonate.

In some embodiments, R may include any suitable amino protecting group,including, but not limited to, carbamate, amide, N-alkyl, orN-aryl-derived protecting groups.

In particular, the carbamate protecting group may include, for example,9-fluorenylmethyl carbamate (Fmoc), t-butyl carbamate (Boc),carboxybenzyl carbamate (cbz), methyl carbamate, ethyl carbamate,9-(2-sulfo)fluorenylmethyl carbamate, 9-(2,7-dibromo)fluorenylmethylcarbamate, 17-tetrabenzol[a,c,g,i]fluorenylmethyl carbamate (Tbfmoc),2-chloro-3-indenylmethyl carbamate (Climoc),2,7-di-t-butyl[9-(10,10-dioxo-10,10,10,10-tetrahydrothioxanthyl)]methylcarbamate (DBD-Tmoc), 1,1-dioxobenzo[b]thiophene-2-ylmethyl carbamate(Bsmoc), 2,2,2-trichloroethyl carbamate (Troc), 2-trimethylsilylethylcarbamate (Teoc), 2-phenylethyl carbamate (hZ), 1,1-dimethyl-2-haloethylcarbamate, 1,1-dimethyl-2,2-dibromoethyl carbamate (DB-t-boc),1,1-dimethyl-2,2,2-trichloroethyl carbamate (TCBoc),1-methyl-1-(4-biphenylyl)ethyl carbamate (Bpoc),1-(3,5-di-t-butylphenyl)-1-methylethyl carbamate (t-Bumeoc),N-2-pivaloylamino)-1,1-dimethylethyl carbamate,2-[(2-nitrophenyl)dithio]-1-phenylethyl carbamate (NpSSPeoc),2-(N,N-dicycloheylcarboxamido)ethyl carbamate, 1-adamanyl carbamate(1-Adoc), cinyl carbamate (Voc), 1-isopropylallyl carbamate (Ipaoc),4-nicrocinnamyl carbamate (Noc), 3-(3′pyridyl)prop-2-enyl carbamate(Paloc), 8-quinolyl carbamate, alkyldithio carbamate, p-methoxybenzylcarbamate (Moz), p-nitrobenzyl carbamate (Pnz), p-bromobenzyl carbamate,p-chlorobenzyl carbamate, 2,4-dichlorobenzyl carbamate,4-methylsulfinylbenzyl carbamate (Msz), diphenylmethyl carbamate,2-methylthioethyl carbamate, 2-methylsulfonylethyl carbamate,2-(p-toluenesulfonyl)ethyl carbamate, [2-(1,3-dithianyl)]methylcarbamate (Dmoc), 4-methylthiophenyl carbamate (Mtpc),2,4-dimethylthiophenyl carbamate (Bmpc), 2-phosphonioethyl carbamate(Peoc), 1,1-dimethyl-2-cyanoethyl carbamate, 2-(4-nitrophenyl)ethylcarbamate, 4-phenylacetoxybenzyl carbamate (PhAcOZ), andm-chloro-p-acyloxybenzyl carbamate. In some embodiments, the carbamateprotecting group is chosen from 9-fluorenylmethyl carbamate (Fmoc),t-butyl carbamate (Boc), and carboxybenzyl carbamate (cbz).

The amide protecting group may include, for example, acetamide,phenylacetamide, 3-phenylpropanamide, pent-4-enamide, picolinamide,3-pyridylcarboxamide, benzamide, p-phenylbenzamide,2-methyl-2-(o-phenylazophenoxy)propanamide), 4-chlorobutanamide,acetoacetamide, 3-(p-hydroxyphenyl)propanamide), and(N′-dithiobenzyloxycarbonylamino)acetamide.

Examples of suitable protecting groups also include tert-butyl, benzyl,4-methoxybenzyl, benzyloxymethyl, phenacyl, allyl, trimethylsilyl,benzyloxycarbonyl, tert-butoxycarbonyl, and acetal and ketalderivatives. In some embodiments, R is selected from trityls,substituted trityls (e.g., monomethoxytrityl (MMTr), dimethoxytrityl(DMTr), trimethoxytrityl (TMTr), 2-chlorotrityl (CITr) andp-bromophenacyloxytrityl (BPTr), pixyls and substituted pixyls (see, forexample, U.S. Publication No. 2007/0276139). In some embodiments, R isselected from trityl, monoalkoxytrityl, dialkoxytrityl, pixyl,alkoxypixyl, fluorenylmethyloxycarbonyl, trifluoroacetyl, acetal, andcyclic acetal.

In some embodiments, R¹ is a hydrophobic separation handle.

A hydrophobic separation handle is as described herein. In someembodiments, the hydrophobic separation handle is also a protectinggroup as described herein. In some embodiments, at least one of R, R¹,and G is a hydrophobic separation handle. For example, only one of R,R¹, and G is a hydrophobic separation handle.

In some embodiments, only one of R¹, R and G is a hydrophobic separationhandle (e.g., a trityl group) as provided herein. For example, if R is ahydrophobic separation handle, then R¹ is absent and G is hydrogen or analkoxy. In some embodiments, R is absent or a protecting group, R¹ is ahydrophobic separation handle, and G is hydrogen or an alkoxy. In someembodiments, wherein more than one of R, R¹ and G is a hydrophobicseparation handle, one of R, R¹ and G is more hydrophobic than theothers (e.g., substantially more hydrophobic). In some embodiments, thehydrophobic separation handle is a substituted or unsubstituted tritylor trityloxy group. For example, only one of R, R¹ and G is asubstituted or unsubstituted trityl or trityloxy group.

A compound as described above can be prepared, for example, bycontacting a water-soluble, non-peptidic and non-nucleotidic polymer, ina water-free solvent (e.g., an organic solvent), with a reagent offormula (4):

wherein:

R⁵ and R⁶ independently from each other represent C₁-C₆-alkyl or R⁵ andR⁶ jointly form a 5- or 6-membered ring with the N to which they arebonded. In some embodiments, R⁵ and R⁶ are independently a C₁-C₆-alkyl.For example, R⁵ and R⁶ can be independently selected from the groupconsisting of methyl, ethyl, propyl, isopropyl, butyl, isobutyl,sec-butyl, tert-butyl, and hexyl. In some embodiments, R⁵ and R⁶ areisopropyl. In some embodiments, R⁵ and R⁶ can jointly form a 5- or6-membered ring with the N to which they are bonded. For example, R⁵ andR⁶ jointly form a pyrrolidine, pyrroline, imidazoline, pyrazolidine,piperidine, 1,2,3,6-tetrahydropyridine, 1,4-dihydropyridine, piperazine,morpholine, thiomorpholine, pyridyl, pyrazinyl, pyrimidinyl,particularly 2- and 4-pyrimidinyl, pyridazinyl, pyrrolyl, particularly2-pyrrolyl, imidazolyl, thiazolyl, oxazolyl, or pyrazolyl, particularly3- and 5-pyrazolyl.

In some embodiments, R⁵ and R⁶ can jointly form a morpholine ring. Theratio of a polymer to a reagent of formula (4) can range from about 1:10to about 10:1 (e.g., about 2:1, about 3:1, about 4:1, about 5:1, about6:1, about 7:1, about 8:1, about 9:1, about 1:2, about 1:3, about 1:4,about 1:5, about 1:6, about 1:7, about 1:81 about 1:9, about 2:8, about3:7, about 4:6 about 5:10, and about 4:8). In some embodiments, theratio of a polymer to a reagent of formula (4) is from about 1:1 toabout 1:10, for example, about 2:1.

An activating reagent can then be added to the mixture of the polymerand the reagent of formula (4). An activating reagent can be any groupsuitable to initiate coupling of the polymer and the reagent of formula(4). Suitable activating reagents include, for example, 1H-tetrazole,5-(ethylthio)-1H-tetrazole (ETT), 5-(benzylthio)-1H-tetrazole (BTT),Activator 42 (5-(3,5-bis(trifluoromethyl)phenyl)-1H-tetrazole),2-ethylthiotetrazole, 2-bezylthiotetrazole, 4,5-dicyanoimidazoleand4,5-dicyanoimidazole (DCI). In some embodiments, an activating agent canbe selected from pyridinium hydrochloride, pyridinium trifluoroacetage,and buffered carboxylic acids.

An oxidizing agent can then be added to oxidize P⁺³ to P⁺⁵. Suitableoxidizing agents and conditions can be readily determined by those ofordinary skill in the art. For example, an oxidant such as RuO₄ ⁻/NMO,Dess-Martin's reagent, DMSO/triflic anhydride, PDC, hydrogen peroxide,inorganic peroxides, nitric acid, nitrates, chlorite, chlorate,perchlorate, hypochlorite, peroxides, iodine, ozone, nitrous oxide,silver oxide, permanganate salts, hexavalent chromium compounds, chromicacid, dichromic acids, chromium trioxide, pyridinium chlorochromate,persulfuric acid, sulfoxides, sulfuric acid, Tollens' reagent,2,2′-dipyridiyldisulfide (DPS), and osmium tetroxide may be used.

In some embodiments, iodine can be used as an oxidizing agent. Forexample, a solution of iodine can be used and prepared by dissolvingiodine in a mixture of pyridine, tetrahydrofuran and water. Elementalsulfur can be used for phosphite oxidation combined with formation ofsulfurized product. In some embodiments, other more soluble and morereactive reagents, such as 3H-1,2-benzothiazol-3-one 1,1-dioxide(Beaucage reagent), phenylacetyl disulfide (PADS), or dimethylthiuram(DTD) can be used. Alternatively, peroxides exemplified by t-butylhydrogen peroxide or m-chlorobenzoyl peroxide may be used for P⁺³ to P⁺⁵oxidations.

In some embodiments, an oxidizing reagent is selected from a groupconsisting of: iodine, hydrogen peroxide, t-butyl hydrogen peroxide,acetone peroxide, sulfur, and thiuram disulfide.

In some embodiments, R is a protecting group or a hydrophobic separationhandle and the method can include purifying the compound usingchromatography (e.g., reverse phase chromatography). In someembodiments, the method also includes removing the protecting group.

For the methods provided above, the deprotection may involve, forexample, either sequential or one-pot deprotection of certain protectinggroups. Suitable reagents and conditions for the deprotection can bereadily determined by those of ordinary skill in the art. For example,deprotection may be achieved upon treatment of the protected compoundunder conditions so that hydroxyl protecting groups, such as acetate,isopropylidine, benzylidine, trityl, and/or pixyl protecting groups, areremoved from the protected compound. The acetate group can be cleavedunder mild conditions, for example, by diluted solution of ammonia or bysolution of potassium carbonate. The benzylidene and isopropylidenegroups can be cleaved by hydrogenation or using acidic hydrolysis asdescribed elsewhere by R. M. Hann et al., J. Am. Chem. Soc., 72, 561(1950). In yet another example, the deprotection can be performed sothat amino protecting groups, such as 9-fluorenylmethyl carbamate(Fmoc), t-butyl carbamate (Boc), and carboxybenzyl carbamate (cbz)protecting groups are cleaved from the protected compound.9-fluorenylmethyl carbamate (FMOC) can be removed under mild conditionswith an amine base (e.g., piperidine) to afford the free amine anddibenzofulvene, as described by E. Atherton et al., “TheFluorenylmethoxycarbonyl Amino Protecting Group” in The Peptides, S.Udenfriend and J. Meienhofer, Academic Press, New York, 1987, p. 1.t-butyl carbamate (Boc) can be removed, as reported by G. L. Stahl etal., J. Org. Chem., 43, 2285 (1978), under acidic conditions (e.g., 3 MHCl in EtOAc). Hydrogenation can be used to cleave the carboxybenzylcarbamate (cbz) protecting group as described by J. Meienhofer et al,Tetrahedron Lett., 29, 2983 (1988).

In some embodiments, deprotection may be performed under anaerobicconditions. The deprotection may also be performed at ambienttemperature or at temperatures of from about 20-60° C. (e.g., 25, 30,35, 40, 45, 50, or 55° C.).

In some cases, a compound as described above can be further purifiedusing precipitation and/or crystallization.

Compounds of Formula (2)

Also provided herein are compounds of formula (2):

or a salt form thereof,wherein:

-   polymer is a linear, water-soluble, non-peptidic, and    non-nucleotidic polymer backbone, wherein each linking group is    bonded at a different terminus of said polymer;-   E and E¹ are independently O or S;-   K and K₁ are independently selected from the group consisting of:    alkylene, alkyleneoxyalkylene, and oligomeric alkyleneoxyalkylene;-   G and G₁ are independently absent or are selected from the group    consisting of: alkoxy and a hydrophobic separation handle;-   each pair of Z¹ and Z² and Z³ and Z⁴ are independently selected from    O and NH, wherein only one of each pair of Z¹ and Z² and Z³ and Z⁴    can be NH;-   L and L¹ are independently selected from the group consisting of: a    divalent radical of a nucleoside, alkylene, alkyleneoxyalkylene,    oligomeric alkyleneoxyalkylene, and unsubstituted and substituted    arylene;-   M and M¹ are independently selected from a protected group that when    deprotected is reactive with a biologically active molecule, a group    reactive with a biologically active molecule, or is a detectable    functional group, wherein M and M¹ are different; and-   R and R¹ are independently absent, hydrogen, a protecting group, or    an activating group;-   wherein when M is a protected group that when deprotected is    reactive with a biologically active molecule, then R is a protecting    group or a hydrophobic separation handle;-   wherein when M is a group reactive with a biologically active    molecule, R is absent, hydrogen, or an activating group;-   wherein when M is a detectable functional group, R is absent or    hydrogen;-   wherein when M¹ is a protected group that when deprotected is    reactive with a biologically active molecule, then R¹ is a    protecting group or a hydrophobic separation handle;-   wherein when M¹ is a group reactive with a biologically active    molecule, R¹ is absent, hydrogen, or an activating group; and-   wherein when M¹ is a detectable functional group, R¹ is absent or    hydrogen.

A polymer can be, for example, poly(alkylene glycol), poly(oxyethylatedpolyol), poly(olefinic alcohol), poly(α-hydroxy acid), poly(vinylalcohol), polyoxazoline, or a copolymer thereof. Such polyalkyleneglycols, include, but are not limited to, polyethylene glycol,polypropylene glycol, polybutylene glycol, and derivatives thereof.Other exemplary embodiments are listed, for example, in commercialsupplier catalogs, such as Shearwater Corporation's catalog“Polyethylene Glycol and Derivatives for Biomedical Applications”(2001). By way of example only, such polymeric poly ether polyols haveaverage molecular weights between about 0.1 kDa to about 100 kDa. By wayof example, such polymeric polyether polyols include, but are notlimited to, between about 500 Da and about 100,000 Da or more. Themolecular weight of the polymer may be between about 500 Da and about100,000 Da, including but not limited to, 100,000 Da, 95,000 Da, 90,000Da, 85,000 Da, 80,000 Da, 75,000 Da, 70,000 Da, 65.000 Da, 60,000 Da,55,000 Da, 50,000 Da, 45,000 Da, 40,000 Da, 35,000 Da, 30,000 Da, 25,000Da, 20,000 Da, 15,000 Da, 10,000 Da, 9,000 Da, 8,000 Da, 7,000 Da, 6,000Da, 5,000 Da, 4,000 Da, 3,000 Da, 2,000 Da, 1,000 Da, 900 Da, 800 Da,700 Da, 600 Da, and 500 Da. In some embodiments, the molecular weight ofthe polymer is between about 500 Da and about 50,000 Da. In someembodiments, the molecular weight of the polymer is between about 500 Daand about 40,000 Da. In some embodiments, the molecular weight of thepolymer is between about 1,000 Da and about 40,000 Da. In someembodiments, the molecular weight of the polymer is between about 5,000Da and about 40.000 Da. In some embodiments, the molecular weight of thepolymer is between about 10.000 Da and about 40,000 Da.

In some embodiments, the polymer is a poly(ethylene glycol) polymer. Themolecular weight of the PEG may be between about 1,000 Da and about100,000 Da, including but not limited to, 100,000 Da, 95,000 Da, 90,000Da, 85,000 Da, 80,000 Da, 75.000 Da, 70,000 Da, 65,000 Da, 60,000 Da,55,000 Da, 50,000 Da, 45,000 Da, 40,000 Da, 35,000 Da, 30,000 Da, 25,000Da, 20,000 Da, 15,000 Da, 10,000 Da, 9,000 Da, 8.000 Da, 7,000 Da, 6,000Da, 5,000 Da, 4,000 Da, 3,000 Da, 2,000 Da, and 1,000 Da. In someembodiments, the molecular weight of the PEG is between about 1,000 Daand about 50,000 Da. In some embodiments, the molecular weight of the nPEG is between about 1,000 Da and about 40,000 Da. In some embodiments,the molecular weight of the PEG is between about 5,000 Da and about40,000 Da. In some embodiments, the molecular weight of the PEG isbetween about 5,000 Da and about 20,000 Da.

In some embodiments, E¹ is oxygen. In some embodiments, E¹ is sulfur. Insome embodiments, E² is oxygen. In some embodiments, E² is sulfur. Insome embodiments, both of E¹ and E² are oxygen.

In some embodiments, K and K¹ are independently selected from a linearor branched alkylene. For example, K and K¹ can be independentlyselected from the group consisting of: methylene, ethylene, propylene,isopropylene, butylene, isobutylene, sec-butylene, tert-butylene, andhexylene. In some embodiments, K and K¹ are independently analkyleneoxyalkylene or an oligomeric alkyleneoxyalkylene. For example, Kand K¹ can be independently a residue from diethylene glycol,triethylene glycol, tetraethylene glycol or hexaethylene glycol. In someembodiments, K and K¹ are independently selected from the groupconsisting of —(CH₂)_(n)— and —((CH₂)_(n)—O—(CH₂)_(m))_(p)—, wherein nis an integer from 1 to 50 (e.g., 1 to 40, 1 to 30, 1 to 25, 1 to 20, 1to 18, 1 to 15, 1 to 12, 1 to 10, 1 to 6, 1 to 6, 1 to 2, 1 to 3, 1 to4, 2 to 50, 5 to 50, 10 to 50, 15 to 50, 25 to 50, 5 to 15, 2 to 12, 20to 30, and 6 to 18), m is an integer from 0 to 50 (e.g., 1 to 40, 1 to30, 1 to 25, 1 to 20, 1 to 18, 1 to 15, 1 to 12, 1 to 10, 1 to 6, 1 to2, 1 to 3, 1 to 4, 2 to 50, 5 to 50, 10 to 50, 15 to 50, 25 to 50, 5 to15, 2 to 12, 20 to 30, and 6 to 18), and each p is independently aninteger from 1 to 10 (e.g., 1 to 8, 1 to 6, 1 to 5, 1 to 3, 2 to 10, 4to 10, 6 to 10, 2 to 8, and 3 to 6).

In some embodiments, G and G¹ are independently a hydrophobic separationhandle. For example, G and G¹ are independently a substituted orunsubstituted trityloxy group. In some embodiments, G and G¹ areindependently selected from the group consisting of monoalkoxysubstituted trityloxy group or dialkoxy substituted trityloxy group.

In some embodiments, one of Z¹ and Z² is NH and the other is O. Forexample, Z¹ is O and Z² is NH; Z¹ is NH and Z² is O. In someembodiments, both Z¹ and Z² are O. In some embodiments, one of Z¹ and Z²is NH and the other is O. For example, Z³ is O and Z⁴ is NH; Z³ is NHand Z⁴ is O. In some embodiments, both Z³ and Z⁴ are O. In someembodiments, one of Z¹ and Z² and Z³ and Z⁴ is NH and the other is O.For example, Z¹ and Z³ are O and Z² and Z⁴ are NH; Z¹ and Z³ are NH andZ² and Z⁴ O. In some embodiments, Z¹ and Z³ are O and Z² and Z⁴ are O.

In some embodiments, L and L¹ are independently selected from a linearor branched alkyl. For example, L and L¹ can be independently selectedfrom the group consisting of: methylene, ethylene, propylene,isopropylene, butylene, isobutylene, sec-butylene, tert-butylene, andhexylene. In some embodiments, L and L¹ are independently analkyleneoxyalkylene or an oligomeric alkyleneoxyalkylene. For example, Land L¹ can be independently a residue from diethylene glycol,triethylene glycol, tetraethylene glycol or hexaethylene glycol. In someembodiments, L and L¹ are independently selected from the groupconsisting of —(CH₂)_(n)— and —((CH₂)_(n)—O—(CH₂)_(m))_(p)—, wherein nis an integer from 1 to 50 (e.g., 1 to 40, 1 to 30, 1 to 25, 1 to 20, 1to 18, 1 to 15, 1 to 12, 1 to 10, 1 to 6, 1 to 6, 1 to 2, 1 to 3, 1 to4, 2 to 50, 5 to 50, 10 to 50, 15 to 50, 25 to 50, 5 to 15, 2 to 12, 20to 30, and 6 to 18), m is an integer from 0 to 50 (e.g., 1 to 40, 1 to30, 1 to 25, 1 to 20, 1 to 18, 1 to 15, 1 to 12, 1 to 10, 1 to 6, 1 to2, 1 to 3, 1 to 4, 2 to 50, 5 to 50, 10 to 50, 15 to 50, 25 to 50, 5 to15, 2 to 12, 20 to 30, and 6 to 18), and each p is independently aninteger from 1 to 10 (e.g., 1 to 8, 1 to 6, 1 to 5, 1 to 3, 2 to 10, 4to 10, 6 to 10, 2 to 8, and 3 to 6).

In some embodiments, L and L¹ are independently a substituted orunsubstituted arylene. For example, L and L¹ can be independently astructure with the formula:

wherein W is a substituent and r is an integer from 0 to 4. For example,W can be selected from the group consisting of: halo, C₁-C₁₀ alkyl,C₂-C₁₀ alkenyl, C₂-C₁₀ alkynyl, C₁-C₁₀ alkoxy, C₅-C₁₂ aralkyl, C₃-C₁₂cycloalkyl, C₄-C₁₂ cycloalkenyl, phenyl, substituted phenyl, toluoyl,xylenyl, biphenyl, C₂-C₁₂ alkoxyalkyl, C₅-C₁₂ alkoxyaryl, C₅-C₁₂aryloxyalkyl, C₇-C₁₂ oxyaryl, C₁-C₆ alkylsulfinyl, C₁-C₁₀ alkylsulfonyl,—(CH₂)_(m)—O—(C₁-C₁₀ alkyl) wherein m is from 1 to 8, aryl, substitutedaryl, substituted alkoxy, fluoroalkyl, heterocyclic radical, substitutedheterocyclic radical, nitroalkyl, —NO₂, —CN, —NR⁹C(O)—(C₁-C₁₀ alkyl),—C(O)—(C₁-C₁₀ alkyl), C₂-C₁₀ alkthioalkyl, —C(O)O—(C₁-C₁₀ alkyl), —OH,—SO₂, ═S, —COOH, —NR⁹ ₂, carbonyl, —C(O)—(C₁-C₁₀ alkyl)-CF₃, —C(O)—CF₃,—C(O)NR⁹ ₂, —(C₁-C₁₀ aryl)-S—(C₆-C₁₀ aryl), —C(O)—(C₆-C₁₀ aryl),—(CH₂)_(m)—O—(CH₂)_(m)—O—(C₁-C₁₀ alkyl) wherein each m is from 1 to 8,—C(O)NR⁹ ₂, —C(S)NR⁹ ₂, —SO₂NR⁹ ₂, —NR⁹C(O)NR⁹ ₂, —NR⁹C(S)NR⁹ ₂, saltsthereof, and the like. Each R⁹ group in the preceding list independentlyincludes, but is not limited to, H, alkyl or substituted alkyl, aryl orsubstituted aryl, or alkylaryl. In some embodiments, W is R¹ asdescribed above.

Non-limiting examples of L and L¹ include:

L and L¹ can also independently be a divalent radical of a nucleoside.For example, L and L¹ can be a divalent radical of a natural nucleoside,such as adenosine, deoxyadenosine, guanosine, deoxyguanosine,5-methyluridine, thymidine, uridine, deoxyuridine, cytidine, anddeoxycytidine.

A group reactive with a biologically active molecule can be selectedfrom the group consisting of: hydroxyl, amine, thiol, carboxyl,aldehyde, glyoxal, dione, alkenyl, alkynyl, alkedienyl, azide,acrylamide, vinyl sulfone, hydrazide, aminoxy, maleimide,dithiopyridine, iodoacetamide. In some embodiments, the group isprotected or further reacted with a group R and R¹ as shown in theformula (2). The point of attachment of such a group is well understoodby those of skill in the art.

In some embodiments, M and/or M¹ is a detectable functional group. Adetectable functional group, as used herein, can be any chemical orsubstance which is used to provide a signal or contrast in imaging. Thesignal enhancing domain can be an organic molecule, metal ion, salt orchelate, particle (particularly iron particle), or labeled peptide,protein, polymer or liposome. For example, a detectable functional groupcan include one or more of a radionuclide, a paramagnetic metal, afluorophore, a dye, and an enzyme substrate. In some embodiments, adetectable functional group is biotin or a fluorophore.

In some embodiments, the detectable functional group is aphysiologically compatible metal chelate compound consisting of one ormore cyclic or acyclic organic chelating agents complexed to one or moremetal ions with atomic numbers 21-29, 42, 44, or 57-83.

For x-ray imaging, the detectable functional group may consist ofiodinated organic molecules or chelates of heavy metal ions of atomicnumbers 57 to 83. In some embodiments, the detectable functional groupis ¹²⁵I-IgG. Examples of suitable compounds are described in M. Sovak,ed., “Radiocontrast Agents,” Springer-Verlag. pp. 23-125 (1984) and U.S.Pat. No. 4,647,447.

For ultrasound imaging, the detectable functional group can consist ofgas-filled bubbles such as Albunex, Echovist, or Levovist, or particlesor metal chelates where the metal ions have atomic numbers 21-29, 42, 44or 57-83. Examples of suitable compounds are described in Tyler et al.,Ultrasonic Imaging. 3, pp. 323-29 (1981) and D. P. Swanson, “EnhancementAgents for Ultrasound: Fundamentals,” Pharmaceuticals in MedicalImaging, pp. 682-87. (1990).

For nuclear radiopharmaceutical imaging or radiotherapy, the detectablefunctional group can consist of a radioactive molecule. In someembodiments, the chelates of Tc, Re, Co, Cu, Au, Ag, Pb, Bi, In, and Gacan be used. In some embodiments, the chelates of Tc-99m can be used.Examples of suitable compounds are described in Rayudu GVS, Radiotracersfor Medical Applications. I, pp. 201 and D. R Swanson et al., ed.,Pharmaceuticals in Medical Imaging, pp. 279-644 (1990).

For ultraviolet/visible/infrared light imaging, the detectablefunctional group can consist of any organic or inorganic dye or anymetal chelate.

For MRI, the detectable functional group can consist of a metal-ligandcomplex of a paramagnetic form of a metal ion with atomic numbers 21-29,42, 44, or 57-83. In some embodiments, the paramagnetic metal is chosenfrom: Gd(III), Fe(III), Mn(II and III), Cr(III), Cu(II), Dy(III),Tb(III), Ho(III), Er(III) and Eu(III). Many suitable chelating ligandsfor MRI agents are known in the art. These can also be used for metalchelates for other forms of biological imaging. For example, an imagingagent can include: Gadovist, Magnevist, Dotarem, Omniscan, and ProHance.

In some embodiments, R and/or R¹ is absent. In some embodiments, Rand/or R¹ is a protecting group. For this purpose, R and/or R¹ mayinclude any suitable protecting group based on the group to beprotected. For example, R and/or R¹ may include any suitable hydroxylfunctional group including, but not limited to, ether, ester, carbonate,or sulfonate protecting groups.

In particular, the ether protecting group may include benzyloxymethyl(BOM), methylthiomethyl (MTM), phenylthiomethyl (PTM), cyanoethyl,2,2-dichloro-1,1-difluoroethyl, 2-chloroethyl, 2-bromoethyl,tetrahydropyranyl (THP), phenacyl, 4-bromophenacyl, allyl, propargyl,t-butyl benzyl, 2,6-dimethylbenzyl, 4-methoxybenzyl (MPM-OAr),o-nitrobenzyl, 2,6-dichlorobenzyl, 3,4-dichlorobenzyl,4-(dimethylamino)carbonylbenzyl, 4-methylsulfinylbenzyl (Msib),9-anthrylemethyl, 4-picolyl, heptafluoro-p-tolyl, tetrafluoro-4-pyridyl,trimethylsilyl (TMS), and protecting groups.

The ester protecting group may include acetoxy (OAc), aryl formate,acetate, levulinate, pivaloate, benzoate, and 9-fluoroenecarboxylate. Inone embodiment, the ester protecting group is an acetoxy group.

The carbonate protecting group may include aryl methyl carbonate,1-adamantyl carbonate (Adoc-OAr), t-butyl carbonate (BOC-OAr),4-methylsulfinylbenzyl carbonate (Msz-OAr), 2,4-dimethylpent-3-ylcarbonate (Doc-OAr), aryl 2,2,2-trichloroethyl carbonate.

The sulfonate protecting groups may include aryl methanesulfonate, aryltoluenesulfonate, and aryl 2-formylbenzenesulfonate.

In some embodiments, R may include any suitable amino protecting group,including, but not limited to, carbamate, amide, N-alkyl, orN-aryl-derived protecting groups.

In particular, the carbamate protecting group may include, for example,9-fluorenylmethyl carbamate (Fmoc), t-butyl carbamate (Boc),carboxybenzyl carbamate (cbz), methyl carbamate, ethyl carbamate,9-(2-sulfo)fluorenylmethyl carbamate, 9-(2,7-dibromo)fluorenylmethylcarbamate, 17-tetrabenzol[a,c,g,i]fluorenylmethyl carbamate (Tbfmoc),2-chloro-3-indenylmethyl carbamate (Climoc),2,7-di-t-butyl[9-(10,10-dioxo-10,10,10,10-tetrahydrothioxanthyl)]methylcarbamate (DBD-Tmoc), 1,1-dioxobenzo[b]thiophene-2-ylmethyl carbamate(Bsmoc), 2,2,2-trichloroethyl carbamate (Troc), 2-trimethylsilylethylcarbamate (Teoc), 2-phenylethyl carbamate (hZ), 1,1-dimethyl-2-haloethylcarbamate, 1,1-dimethyl-2,2-dibromoethyl carbamate (DB-t-boc),1,1-dimethyl-2,2,2-trichloroethyl carbamate (TCBoc),1-methyl-1-(4-biphenylyl)ethyl carbamate (Bpoc),1-(3,5-di-t-butylphenyl)-1-methylethyl carbamate (7-Bumeoc),N-2-pivaloylamino)-1,1-dimethylethyl carbamate,2-[(2-nitrophenyl)dithio]-1-phenylethyl carbamate (NpSSPeoc),2-(N,N-dicycloheylcarboxamido)ethyl carbamate, 1-adamanyl carbamate(1-Adoc), cinyl carbamate (Voc), 1-isopropylallyl carbamate (Ipaoc),4-nicrocinnamyl carbamate (Noc), 3-(3′pyridyl)prop-2-enyl carbamate(Paloc), 8-quinolyl carbamate, alkyldithio carbamate, p-methoxybenzylcarbamate (Moz), p-nitrobenzyl carbamate (Pnz), p-bromobenzyl carbamate,p-chlorobenzyl carbamate, 2,4-dichlorobenzyl carbamate,4-methylsulfinylbenzyl carbamate (Msz), diphenylmethyl carbamate,2-methylthioethyl carbamate, 2-methylsulfonylethyl carbamate,2-(p-toluenesulfonyl)ethyl carbamate, [2-(1,3-dithianyl)]methylcarbamate (Dmoc), 4-methylthiophenyl carbamate (Mtpc),2,4-dimethylthiophenyl carbamate (Bmpc), 2-phosphonioethyl carbamate(Peoc), 1,1-dimethyl-2-cyanoethyl carbamate, 2-(4-nitrophenyl)ethylcarbamate, 4-phenylacetoxybenzyl carbamate (PhAcOZ), andm-chloro-p-acyloxybenzyl carbamate. In some embodiments, the carbamateprotecting group is chosen from 9-fluorenylmethyl carbamate (Fmoc),t-butyl carbamate (Boc), and carboxybenzyl carbamate (cbz).

The amide protecting group may include, for example, acetamide,phenylacetamide, 3-phenylpropanamide, pent-4-enamide, picolinamide,3-pyridylcarboxamide, benzamide, p-phenylbenzamide,2-methyl-2-(o-phenylazophenoxy)propanamide), 4-chlorobutanamide,acetoacetamide, 3-(p-hydroxyphenyl)propanamide), and(N′-dithiobenzyloxycarbonylamino)acetamide.

Examples of suitable protecting groups also include tert-butyl, benzyl,4-methoxybenzyl, benzyloxymethyl, phenacyl, allyl, trimethylsilyl,benzyloxycarbonyl, tert-butoxycarbonyl, and acetal and ketalderivatives. In some embodiments, R is selected from trityls,substituted trityls (e.g., monomethoxytrityl (MMTr), dimethoxytrityl(DMTr), trimethoxytrityl (TMTr), 2-chlorotrityl (CITr) andp-bromophenacyloxytrityl (BPTr), pixyls and substituted pixyls (see, forexample, U.S. Publication No. 2007/0276139). In some embodiments, R isselected from trityl, monoalkoxytrityl, dialkoxytrityl, pixyl,alkoxypixyl, fluorenylmethyloxycarbonyl, trifluoroacetyl, acetal, andcyclic acetal.

In some embodiments, R and/or R¹ is a hydrophobic separation handle.

A hydrophobic separation handle is as described herein. In someembodiments, the hydrophobic separation handle is also a protectinggroup as described herein. In some embodiments, at least one of R, R¹,G, and G¹ is a hydrophobic separation handle.

In some embodiments, only one of R and G and R¹ and G¹ is a hydrophobicseparation handle (e.g., a trityl group) as provided herein. Forexample, if R is a hydrophobic separation handle, then G is hydrogen oran alkoxy. Alternatively, if R¹ is a hydrophobic separation handle, thenG¹ is absent or an alkoxy. In some embodiments, R is absent or aprotecting group, R¹ is a hydrophobic separation handle, and G and G¹are independently absent or an alkoxy, wherein R¹ is more hydrophobicthan R. In some embodiments, R¹ is absent or a protecting group, R is ahydrophobic separation handle, and G and G¹ are independently absent oran alkoxy, wherein R is more hydrophobic than R¹. In some embodiments,the hydrophobic separation handle is a substituted or unsubstitutedtrityl or trityloxy group. For example, only one of R, R¹, G, and G¹ isa substituted or unsubstituted trityl or trityloxy group.

A compound as described above can be prepared, for example, bycontacting a water-soluble, non-peptidic and non-nucleotidic polymer, ina water-free solvent (e.g., an organic solvent), with a reagent selectedfrom formula (5):

wherein:

-   R⁵ and R⁶ independently from each other represent C₁-C₆-alkyl or R⁵    and R⁶ jointly form a 5- or 6-membered ring with the N to which they    are bonded, and formula (6):

wherein:

-   R⁷ and R⁸ independently from each other represent C₁-C₆-alkyl or R⁷    and R⁸ jointly form a 5- or 6-membered ring with the N to which they    are bonded;-   under conditions that facilitate formation of monoderivatized    product.

In some embodiments, R⁵ and R⁶ are independently a C₁-C₆-alkyl. Forexample, R⁵ and R⁶ can be independently selected from the groupconsisting of methyl, ethyl, propyl, isopropyl, butyl, isobutyl,sec-butyl, tert-butyl, and hexyl. In some embodiments, R⁵ and R⁶ areisopropyl. In some embodiments, R⁵ and R⁶ jointly form a 5- or6-membered ring with the N to which they are bonded. For example, R⁵ andR⁶ jointly form a pyrrolidine, pyrroline, imidazoline, pyrazolidine,piperidine, 1,2,3,6-tetrahydropyridine, 1,4-dihydropyridine, piperazine,morpholine, thiomorpholine, pyridyl, pyrazinyl, pyrimidinyl,particularly 2- and 4-pyrimidinyl, pyridazinyl, pyrrolyl, particularly2-pyrrolyl, imidazolyl, thiazolyl, oxazolyl, and pyrazolyl, particularly3- and 5-pyrazolyl. In some embodiments, R⁵ and R⁶ jointly form amorpholine ring.

In some embodiments, R⁷ and R⁸ are independently a C₁-C₆-alkyl. Forexample, R⁷ and R⁸ can be independently selected from the groupconsisting of methyl, ethyl, propyl, isopropyl, butyl, isobutyl,sec-butyl, tert-butyl, and hexyl. In some embodiments, R⁷ and R⁸ areisopropyl. In some embodiments, R⁷ and R⁸ jointly form a 5- or6-membered ring with the N to which they are bonded. For example, R⁷ andR⁸ jointly form a pyrrolidine, pyrroline, imidazoline, pyrazolidine,piperidine, 1,2,3,6-tetrahydropyridine, 1,4-dihydropyridine, piperazine,morpholine, thiomorpholine, pyridyl, pyrazinyl, pyrimidinyl,particularly 2- and 4-pyrimidinyl, pyridazinyl, pyrrolyl, particularly2-pyrrolyl, imidazolyl, thiazolyl, oxazolyl, and pyrazolyl, particularly3- and 5-pyrazolyl. In some embodiments, R⁷ and R⁸ jointly form amorpholine ring.

The ratio of a polymer to a reagent of formula (5) or (6) can range fromabout 1:10 to about 10:1 (e.g., about 2:1, about 3:1, about 4:1, about5:1, about 6:1, about 7:1, about 8:1, about 9:1, about 1:2, about 1:3,about 1:4, about 1:5, about 1:6, about 1:7, about 1:81 about 1:9, about2:8, about 3:7, about 4:6 about 5:10, and about 4:8). In someembodiments, the ratio of a polymer to a reagent of formula (5) or (6)is from about 1:1 to about 1:10. In some embodiments, the ratio of apolymer to a reagent of formula (5) or (6) is about 2:1.

In some embodiments, conditions that facilitate formation of amonoderivatized product include the addition of an activating reagent.An activating reagent is then added to the mixture of the polymer andthe reagent of formula (4) or (5). An activating reagent can be anygroup suitable to initiate coupling of the polymer and the reagent offormula (4). Suitable activating reagents include, for example,1H-tetrazole, 5-(ethylthio)-1H-tetrazole (ETT),5-(benzylthio)-1H-tetrazole (BTT), Activator 42(5-(3,5-bis(trifluoromethyl)phenyl)-1H-tetrazole), 2-ethylthiotetrazole,2-bezylthiotetrazole, 4,5-dicyanoimidazoleand 4,5-dicyanoimidazole(DCI). In some embodiments, an activating agent can be selected frompyridinium hydrochloride, pyridinium trifluoroacetage, and bufferedcarboxylic acids.

In some embodiments, conditions that facilitate formation of amonoderivatized product include addition of an oxidizing agent tooxidize P⁺³ to P⁺⁵. Suitable oxidizing agents and conditions can bereadily determined by those of ordinary skill in the art. For example,an oxidant such as RuO₄ ⁻/NMO, Dess-Martin's reagent, DMSO/triflicanhydride, PDC, hydrogen peroxide, inorganic peroxides, nitric acid,nitrates, chlorite, chlorate, perchlorate, hypochlorite, peroxide,iodine, ozone, nitrous oxide, silver oxide, permanganate salts,hexavalent chromium compounds, chromic acid, dichromic acids, chromiumtrioxide, pyridinium chlorochromate, persulfuric acid, sulfoxides,sulfuric acid, Tollens' reagent, 2,2′-dipyridiyldisulfide (DPS), andosmium tetroxide may be used.

In some embodiments, iodine can be used as an oxidizing agent. Forexample, a solution of iodine can be used and prepared by dissolvingiodine in a mixture of pyridine, tetrahydrofuran and water. Elementalsulfur can be used for phosphite oxidation combined with formation ofsulfurized product. In some embodiments, other more soluble and morereactive reagents, such as 3H-1,2-benzothiazol-3-one 1,1-dioxide(Beaucage reagent), phenylacetyl disulfide (PADS) or dimethylthiuram(DTD) can be used. Alternatively, peroxides exemplified by t-butylhydrogen peroxide or m-chlorobenzoyl peroxide may be used for P⁺³ to P⁺⁵oxidations.

In some embodiments, an oxidizing reagent is selected from a groupconsisting of: iodine, hydrogen peroxide, t-butyl hydrogen peroxide,acetone peroxide, sulfur, and thiuram disulfide.

In some embodiments, R and/or R¹ is a protecting group or a hydrophobicseparation handle. In some embodiments, the method can further includepurifying the monoderivatized compound using chromatography (e.g.,reverse phase chromatography).

To the monoderivatized product, a reagent of formula (4) or formula (5)is added under conditions that facilitate the conversion of themonoderivatized product to a compound of formula (2). In someembodiments, the reagent is different from the reagent used to preparethe monoderivatized product. In some embodiments, the reagent is thesame as that used to prepare the monoderivatized product.

In some embodiments, the conditions are such that conversion of themonoderivatized product to the compound of formula (2) is quantitative.

In some embodiments, conditions that facilitate formation of a compoundof formula (2) include the addition of an activating reagent. Anactivating reagent is then added to the mixture of the monoderivatizedproduct and the reagent of formula (5) or (6). An activating reagent canbe any group suitable to initiate coupling of the polymer and thereagent of formula (5) or (6). Suitable activating reagents include, forexample, 1H-tetrazole, 5-(ethylthio)-1H-tetrazole (ETT),5-(benzylthio)-1H-tetrazole (BTT), Activator 42(5-(3,5-bis(trifluoromethyl)phenyl)-1H-tetrazole), 2-ethylthiotetrazole,2-bezylthiotetrazole, 4,5-dicyanoimidazoleand 4,5-dicyanoimidazole(DCI). In some embodiments, an activating agent can be selected frompyridinium hydrochloride, pyridinium trifluoroacetage, and bufferedcarboxylic acids.

In some embodiments, conditions that facilitate formation of a compoundof formula (2) include addition of an oxidizing agent to oxidize P⁺³ toP⁺⁵. Suitable oxidizing agents and conditions can be readily determinedby those of ordinary skill in the art. For example, an oxidant such asRuO₄ ⁻/NMO, Dess-Martin's reagent, DMSO/triflic anhydride, PDC, hydrogenperoxide, inorganic peroxides, nitric acid, nitrates, chlorite,chlorate, perchlorate, hypochlorite, peroxide, iodine, ozone, nitrousoxide, silver oxide, permanganate salts, hexavalent chromium compounds,chromic acid, dichromic acids, chromium trioxide, pyridiniumchlorochromate, persulfuric acid, sulfoxides, sulfuric acid, Tollens'reagent, 2,2′-dipyridiyldisulfide (DPS), and osmium tetroxide may beused.

In some embodiments, iodine can be used as an oxidizing agent. Forexample, a solution of iodine can be used and prepared by dissolvingiodine in a mixture of pyridine, tetrahydrofuran and water. Elementalsulfur can be used for phosphite oxidation combined with formation ofsulfurized product. In some embodiments, other more soluble and morereactive reagents, such as 3H-1,2-benzothiazol-3-one 1,1-dioxide(Beaucage reagent), phenylacetyl disulfide (PADS) or dimethylthiuram(DTD) can be used. Alternatively, peroxides exemplified by t-butylhydrogen peroxide or m-chlorobenzoyl peroxide may be used for P⁺³ to P⁺⁵oxidations.

In some embodiments, an oxidizing reagent is selected from a groupconsisting of: iodine, hydrogen peroxide, t-butyl hydrogen peroxide,acetone peroxide, sulfur, and thiuram disulfide.

In some embodiments, R and/or R¹ is a protecting group or a hydrophobicseparation handle. In some embodiments, the method can further includepurifying the monoderivatized compound using chromatography (e.g.,reverse phase chromatography). In some embodiments, the method furtherincludes removal of one or more of the protecting groups. In someembodiments, the method further includes removal of one or more of thehydrophobic separation handles.

For the methods provided above, the deprotection may involve, forexample, either sequential or one-pot deprotection of certain protectinggroups. Suitable reagents and conditions for the deprotection can bereadily determined by those of ordinary skill in the art. For example,deprotection may be achieved upon treatment of the protected compoundunder conditions so that hydroxyl protecting groups, such as acetate,isopropylidine, benzylidine, trityl, and pixyl protecting groups, areremoved from the protected compound. The acetate group can be cleavedunder mild conditions, for example, by diluted solution of ammonia or bysolution of potassium carbonate. The benzylidene and isopropylidenegroups can be cleaved by hydrogenation or using acidic hydrolysis asreported by R. M. Hann et al., J. Am. Chem. Soc., 72, 561 (1950). In yetanother example, the deprotection can be performed so that aminoprotecting groups, such as 9-fluorenylmethyl carbamate (Fmoc), t-butylcarbamate (Boc), and carboxybenzyl carbamate (cbz) protecting groups arecleaved from the protected compound. 9-fluorenylmethyl carbamate (FMOC)can be removed under mild conditions with an amine base (e.g.,piperidine) to afford the free amine and dibenzofulvene, as described byE. Atherton et al, “The Fluorenylmethoxycarbonyl Amino Protecting Group”in The Peptides, S. Udenfriend and J. Meienhofer, Academic Press, NewYork, 1987, p. 1. t-butyl carbamate (Boc) can be removed, as reported byG. L. Stahl et al., J. Org. Chem., 43, 2285 (1978), under acidicconditions (e.g., 3 M HCl in EtOAc). Hydrogenation can be used to cleavethe carboxybenzyl carbamate (cbz) protecting group as described by J.Meienhofer et al, Tetrahedron Lett., 29, 2983 (1988).

In some embodiments, deprotection may be performed under anaerobicconditions. The deprotection may also be performed at ambienttemperature or at temperatures of from about 20-60° C. (e.g., 25, 30,35, 40, 45, 50, or 55° C.).

In some embodiments, the method can also include isolating the compoundby precipitation or crystallization.

Compounds of Formula (3)

Also provided herein is a compound of formula (3):

or a salt form thereof,wherein:

-   polymer is a linear, water-soluble, non-peptidic, and    non-nucleotidic polymer backbone, wherein M² and the    phosphonate-derived functional group are bonded at a different    terminus of said polymer;-   E and E¹ are independently O or S;-   K is selected from the group consisting of: alkylene,    alkyleneoxyalkylene, and oligomeric alkyleneoxyalkylene;-   G is selected from the group consisting of hydrogen, alkoxy and a    hydrophobic separation handle;-   Z¹ and Z² are independently selected from O and NH, wherein only one    of Z¹ and Z² can be NH;-   L is selected from the group consisting of: a divalent radical of a    nucleoside, alkylene, alkyleneoxyalkylene, oligomeric    alkyleneoxyalkylene, and unsubstituted and substituted arylene;-   M is selected from a protected group that when deprotected is    reactive with a biologically active molecule, a group reactive with    a biologically active molecule, or is a detectable functional group;-   M² is selected from O, S or NH; and-   R is absent, a protecting group, a hydrophobic separation handle, or    an activating group;-   R² is hydrogen or a protecting group; wherein when M is a protected    group that when deprotected is reactive with a biologically active    molecule, then R is a protecting group or a hydrophobic separation    handle;-   wherein when M is a group reactive with a biologically active    molecule, R is absent, hydrogen, or an activating group; and-   wherein when M is a detectable functional group, R is absent or    hydrogen.

A polymer can be, for example, poly(alkylene glycol), poly(oxyethylatedpolyol), poly(olefinic alcohol), poly(α-hydroxy acid), poly(vinylalcohol), polyoxazoline, or a copolymer thereof. Such polyalkyleneglycols, include, but are not limited to, polyethylene glycol,polypropylene glycol, polybutylene glycol, and derivatives thereof.Other exemplary embodiments are listed, for example, in commercialsupplier catalogs, such as Shearwater Corporation's catalog“Polyethylene Glycol and Derivatives for Biomedical Applications”(2001). By way of example only, such polymeric poly ether polyols haveaverage molecular weights between about 0.1 kDa to about 100 kDa. By wayof example, such polymeric polyether polyols include, but are notlimited to, between about 500 Da and about 100,000 Da or more. Themolecular weight of the polymer may be between about 500 Da and about100,000 Da, including but not limited to, 100,000 Da, 95,000 Da, 90,000Da, 85,000 Da, 80,000 Da, 75,000 Da, 70,000 Da, 65,000 Da, 60,000 Da,55,000 Da, 50,000 Da, 45,000 Da, 40,000 Da, 35,000 Da, 30,000 Da, 25,000Da, 20,000 Da, 15,000 Da, 10,000 Da, 9,000 Da, 8,000 Da, 7,000 Da, 6,000Da, 5,000 Da, 4,000 Da, 3,000 Da, 2,000 Da, 1,000 Da, 900 Da, 800 Da,700 Da, 600 Da, and 500 Da. In some embodiments, the molecular weight ofthe polymer is between about 500 Da and about 50,000 Da. In someembodiments, the molecular weight of the polymer is between about 500 Daand about 40,000 Da. In some embodiments, the molecular weight of thepolymer is between about 1,000 Da and about 40,000 Da. In someembodiments, the molecular weight of the polymer is between about 5,000Da and about 40.000 Da. In some embodiments, the molecular weight of thepolymer is between about 10.000 Da and about 40,000 Da.

In some embodiments, the polymer is a poly(ethylene glycol) polymer. Themolecular weight of the PEG may be between about 1,000 Da and about100,000 Da, including but not limited to, 100,000 Da, 95,000 Da, 90,000Da, 85,000 Da, 80,000 Da, 75.000 Da, 70,000 Da, 65,000 Da, 60,000 Da,55,000 Da, 50,000 Da, 45,000 Da, 40,000 Da, 35,000 Da, 30,000 Da, 25,000Da, 20,000 Da, 15,000 Da, 10,000 Da, 9,000 Da, 8.000 Da, 7,000 Da, 6,000Da, 5,000 Da, 4,000 Da, 3,000 Da, 2,000 Da, and 1,000 Da. In someembodiments, the molecular weight of the PEG is between about 1,000 Daand about 50,000 Da. In some embodiments, the molecular weight of the nPEG is between about 1,000 Da and about 40,000 Da. In some embodiments,the molecular weight of the PEG is between about 5,000 Da and about40,000 Da. In some embodiments, the molecular weight of the PEG isbetween about 5,000 Da and about 20,000 Da.

In some embodiments, E is oxygen. In some embodiments, E is sulfur.

In some embodiments, K is a linear or branched alkylene. For example, Kcan be selected from the group consisting of: methylene, ethylene,propylene, isopropylene, butylene, isobutylene, sec-butylene,tert-butylene, and hexylene. In some embodiments, K can be analkyleneoxyalkylene or an oligomeric alkyleneoxyalkylene. For example, Kcan be a residue from diethylene glycol, triethylene glycol,tetraethylene glycol or hexaethylene glycol. In some embodiments, K isselected from the group consisting of —(CH₂)_(n)— and—((CH₂)_(n)—O—(CH₂)_(m))_(p)—, wherein n is an integer from 1 to 50(e.g., 1 to 40, 1 to 30, 1 to 25, 1 to 20, 1 to 18, 1 to 15, 1 to 12, 1to 10, 1 to 6, 1 to 6, 1 to 2, 1 to 3, 1 to 4, 2 to 50, 5 to 50, 10 to50, 15 to 50, 25 to 50, 5 to 15, 2 to 12, 20 to 30, and 6 to 18), m isan integer from 0 to 50 (e.g., 1 to 40, 1 to 30, 1 to 25, 1 to 20, 1 to18, 1 to 15, 1 to 12, 1 to 10, 1 to 6, 1 to 2, 1 to 3, 1 to 4, 2 to 50,5 to 50, 10 to 50, 15 to 50, 25 to 50, 5 to 15, 2 to 12, 20 to 30, and 6to 18), and each p is independently an integer from 1 to 10 (e.g., 1 to8, 1 to 6, 1 to 5, 1 to 3, 2 to 10, 4 to 10, 6 to 10, 2 to 8, and 3 to6).

In some embodiments, G is a hydrophobic separation handle. For example,G can be a substituted or unsubstituted trityloxy group. In someembodiments, G is selected from the group consisting of monoalkoxysubstituted trityloxy group or dialkoxy substituted trityloxy group.

In some embodiments, one of Z¹ and Z² is NH and the other is O. Forexample, Z¹ is O and Z² is NH; Z¹ is NH and Z² is O. In someembodiments, both Z¹ and Z² are O.

In some embodiments, L is a linear or branched alkyl. For example, L canbe selected from the group consisting of: methylene, ethylene,propylene, isopropylene, butylene, isobutylene, sec-butylene,tert-butylene, and hexylene. In some embodiments, L can be analkyleneoxyalkylene or an oligomeric alkyleneoxyalkylene. For example, Lcan be a residue from diethylene glycol, triethylene glycol,tetraethylene glycol or hexaethylene glycol. In some embodiments, L isselected from the group consisting of —(CH₂)_(n)— and—((CH₂)_(n)—O—(CH₂)_(m))_(p)—, wherein n is an integer from 1 to 50(e.g., 1 to 40, 1 to 30, 1 to 25, 1 to 20, 1 to 18, 1 to 15, 1 to 12, 1to 10, 1 to 6, 1 to 6, 1 to 2, 1 to 3, 1 to 4, 2 to 50, 5 to 50, 10 to50, 15 to 50, 25 to 50, 5 to 15, 2 to 12, 20 to 30, and 6 to 18), m isan integer from 0 to 50 (e.g., 1 to 40, 1 to 30, 1 to 25, 1 to 20, 1 to18, 1 to 15, 1 to 12, 1 to 10, 1 to 6, 1 to 2, 1 to 3, 1 to 4, 2 to 50,5 to 50, 10 to 50, 15 to 50, 25 to 50, 5 to 15, 2 to 12, 20 to 30, and 6to 18), and each p is independently an integer from 1 to 10 (e.g., 1 to8, 1 to 6, 1 to 5, 1 to 3, 2 to 10, 4 to 10, 6 to 10, 2 to 8, and 3 to6).

In some embodiments, L is a substituted or unsubstituted arylene. Forexample, L can be a structure with the formula:

wherein W is a substituent and r is an integer from 0 to 4. For example,W can be selected from the group consisting of: halo, C₁-C₁₀ alkyl,C₂-C₁₀ alkenyl, C₂-C₁₀ alkynyl, C₁-C₁₀ alkoxy, C₅-C₁₂ aralkyl, C₃-C₁₂cycloalkyl, C₄-C₁₂ cycloalkenyl, phenyl, substituted phenyl, toluoyl,xylenyl, biphenyl, C₂-C₁₂ alkoxyalkyl, C₅-C₁₂ alkoxyaryl, C₅-C₁₂aryloxyalkyl, C₇-C₁₂ oxyaryl, C₁-C₆ alkylsulfinyl, C₁-C₁₀ alkylsulfonyl,—(CH₂)_(m)—O—(C₁-C₁₀ alkyl) wherein m is from 1 to 8, aryl, substitutedaryl, substituted alkoxy, fluoroalkyl, heterocyclic radical, substitutedheterocyclic radical, nitroalkyl, —NO₂, —CN, —NR⁹C(O)—(C₁-C₁₀ alkyl),—C(O)—(C₁-C₁₀ alkyl), C₂-C₁₀ alkthioalkyl, —C(O)O—(C₁-C₁₀ alkyl), —OH,—SO₂, ═S, —COOH, —NR⁹ ₂, carbonyl, —C(O)—(C₁-C₁₀ alkyl)-CF₃, —C(O)—CF₃,—C(O)NR⁹ ₂, —(C₁-C₁₀ aryl)-S—(C₆-C₁₀ aryl), —C(O)—(C₆-C₁₀ aryl),—(CH₂)_(m)—O—(CH₂)_(m)—O—(C₁-C₁₀ alkyl) wherein each m is from 1 to 8,—C(O)NR⁹ ₂, —C(S)NR⁹ ₂, —SO₂NR⁹ ₂, —NR⁹C(O)NR⁹ ₂, —NR⁹C(S)NR⁹ ₂, saltsthereof, and the like. Each R⁹ group in the preceding list independentlyincludes, but is not limited to, H, alkyl or substituted alkyl, aryl orsubstituted aryl, or alkylaryl. In some embodiments, W is R¹ asdescribed above.

Non-limiting examples of L include:

L can also be a divalent radical of a nucleoside. For example, L can bea divalent radical of a natural nucleoside, such as adenosine,deoxyadenosine, guanosine, deoxyguanosine, 5-methyluridine, thymidine,uridine, deoxyuridine, cytidine, and deoxycytidine.

A group reactive with a biologically active molecule can be selectedfrom the group consisting of: hydroxyl, amine, thiol, carboxyl,aldehyde, glyoxal, dione, alkenyl, alkynyl, alkedienyl, azide,acrylamide, vinyl sulfone, hydrazide, aminoxy, maleimide,dithiopyridine, iodoacetamide. In some embodiments, the group isprotected or further reacted with a group R as shown in the structure offormula (3). The point of attachment of such a group is well understoodby those of skill in the art.

In some embodiments, M is a detectable functional group. A detectablefunctional group, as used herein, can be any chemical or substance whichis used to provide a signal or contrast in imaging. The signal enhancingdomain can be an organic molecule, metal ion, salt or chelate, particle(particularly iron particle), or labeled peptide, protein, polymer orliposome. For example, a detectable functional group can include one ormore of a radionuclide, a paramagnetic metal, a fluorophore, a dye, andan enzyme substrate. In some embodiments, a detectable functional groupis biotin or a fluorophore.

In some embodiments, the detectable functional group is aphysiologically compatible metal chelate compound consisting of one ormore cyclic or acyclic organic chelating agents complexed to one or moremetal ions with atomic numbers 21-29, 42, 44, or 57-83.

For x-ray imaging, the detectable functional group may consist ofiodinated organic molecules or chelates of heavy metal ions of atomicnumbers 57 to 83. In some embodiments, the detectable functional groupis ¹²⁵I-IgG. Examples of suitable compounds are described in M. Sovak,ed., “Radiocontrast Agents,” Springer-Verlag. pp. 23-125 (1984) and U.S.Pat. No. 4,647,447.

For ultrasound imaging, the detectable functional group can consist ofgas-filled bubbles such as Albunex, Echovist, or Levovist, or particlesor metal chelates where the metal ions have atomic numbers 21-29, 42, 44or 57-83. Examples of suitable compounds are described in Tyler et al.,Ultrasonic Imaging. 3, pp. 323-29 (1981) and D. P. Swanson, “EnhancementAgents for Ultrasound: Fundamentals,” Pharmaceuticals in MedicalImaging, pp. 682-87. (1990).

For nuclear radiopharmaceutical imaging or radiotherapy, the detectablefunctional group can consist of a radioactive molecule. In someembodiments, the chelates of Tc, Re, Co, Cu, Au, Ag, Pb, Bi, In, and Gacan be used. In some embodiments, the chelates of Tc-99m can be used.Examples of suitable compounds are described in Rayudu GVS, Radiotracersfor Medical Applications. I, pp. 201 and D. R Swanson et al., ed.,Pharmaceuticals in Medical Imaging, pp. 279-644 (1990).

For ultraviolet/visible/infrared light imaging, the detectablefunctional group can consist of any organic or inorganic dye or anymetal chelate.

For MRI, the detectable functional group can consist of a metal-ligandcomplex of a paramagnetic form of a metal ion with atomic numbers 21-29,42, 44, or 57-83. In some embodiments, the paramagnetic metal is chosenfrom: Gd(III), Fe(III), Mn(II and III), Cr(III), Cu(II), Dy(III),Tb(III), Ho(III), Er(III) and Eu(III). Many suitable chelating ligandsfor MRI agents are known in the art. These can also be used for metalchelates for other forms of biological imaging. For example, an imagingagent can include: Gadovist, Magnevist, Dotarem, Omniscan, and ProHance.

In some embodiments, R is absent.

In some embodiments, R² is hydrogen.

In some embodiments, R and/or R² is a protecting group. For thispurpose, R and/or R² may include any suitable protecting group based onthe group to be protected. For example, R and/or R² may include anysuitable hydroxyl functional group including, but not limited to, ether,ester, carbonate, or sulfonate protecting groups.

In particular, the ether protecting group may include benzyloxymethyl(BOM), methylthiomethyl (MTM), phenylthiomethyl (PTM), cyanoethyl,2,2-dichloro-1,1-difluoroethyl, 2-chloroethyl, 2-bromoethyl,tetrahydropyranyl (THP), phenacyl, 4-bromophenacyl, allyl, propargyl,t-butyl benzyl, 2,6-dimethylbenzyl, 4-methoxybenzyl (MPM-OAr),o-nitrobenzyl, 2,6-dichlorobenzyl, 3,4-dichlorobenzyl,4-(dimethylamino)carbonylbenzyl, 4-methylsulfinylbenzyl (Msib),9-anthrylemethyl, 4-picolyl, heptafluoro-p-tolyl, tetrafluoro-4-pyridyl,trimethylsilyl (TMS), and protecting groups.

The ester protecting group may include acetoxy (OAc), aryl formate,acetate, levulinate, pivaloate, benzoate, and 9-fluoroenecarboxylate. Inone embodiment, the ester protecting group is an acetoxy group.

The carbonate protecting group may include aryl methyl carbonate,1-adamantyl carbonate (Adoc-OAr), t-butyl carbonate (BOC-OAr),4-methylsulfinylbenzyl carbonate (Msz-OAr), 2,4-dimethylpent-3-ylcarbonate (Doc-OAr), aryl 2,2,2-trichloroethyl carbonate.

The sulfonate protecting groups may include aryl methanesulfonate, aryltoluenesulfonate, and aryl 2-formylbenzenesulfonate.

In some embodiments, R may include any suitable amino protecting group,including, but not limited to, carbamate, amide, N-alkyl, orN-aryl-derived protecting groups.

In particular, the carbamate protecting group may include, for example,9-fluorenylmethyl carbamate (Fmoc), t-butyl carbamate (Boc),carboxybenzyl carbamate (cbz), methyl carbamate, ethyl carbamate,9-(2-sulfo)fluorenylmethyl carbamate, 9-(2,7-dibromo)fluorenylmethylcarbamate, 17-tetrabenzol[a,c,g,i]fluorenylmethyl carbamate (Tbfmoc),2-chloro-3-indenylmethyl carbamate (Climoc),2,7-di-t-butyl[9-(10,10-dioxo-10,10,10,10-tetrahydrothioxanthyl)]methylcarbamate (DBD-Tmoc), 1,1-dioxobenzo[b]thiophene-2-ylmethyl carbamate(Bsmoc), 2,2,2-trichloroethyl carbamate (Troc), 2-trimethylsilylethylcarbamate (Teoc), 2-phenylethyl carbamate (hZ), 1,1-dimethyl-2-haloethylcarbamate, 1,1-dimethyl-2,2-dibromoethyl carbamate (DB-t-boc),1,1-dimethyl-2,2,2-trichloroethyl carbamate (TCBoc),1-methyl-1-(4-biphenylyl)ethyl carbamate (Bpoc),1-(3,5-di-t-butylphenyl)-1-methylethyl carbamate (t-Bumeoc),N-2-pivaloylamino)-1,1-dimethylethyl carbamate,2-[(2-nitrophenyl)dithio]-1-phenylethyl carbamate (NpSSPeoc),2-(N,N-dicycloheylcarboxamido)ethyl carbamate, 1-adamanyl carbamate(1-Adoc), cinyl carbamate (Voc), 1-isopropylallyl carbamate (Ipaoc),4-nicrocinnamyl carbamate (Noc), 3-(3′pyridyl)prop-2-enyl carbamate(Paloc), 8-quinolyl carbamate, alkyldithio carbamate, p-methoxybenzylcarbamate (Moz), p-nitrobenzyl carbamate (Pnz), p-bromobenzyl carbamate,p-chlorobenzyl carbamate, 2,4-dichlorobenzyl carbamate,4-methylsulfinylbenzyl carbamate (Msz), diphenylmethyl carbamate,2-methylthioethyl carbamate, 2-methylsulfonylethyl carbamate,2-(p-toluenesulfonyl)ethyl carbamate, [2-(1,3-dithianyl)]methylcarbamate (Dmoc), 4-methylthiophenyl carbamate (Mtpc),2,4-dimethylthiophenyl carbamate (Bmpc), 2-phosphonioethyl carbamate(Peoc), 1,1-dimethyl-2-cyanoethyl carbamate, 2-(4-nitrophenyl)ethylcarbamate, 4-phenylacetoxybenzyl carbamate (PhAcOZ), andm-chloro-p-acyloxybenzyl carbamate. In some embodiments, the carbamateprotecting group is chosen from 9-fluorenylmethyl carbamate (Fmoc),t-butyl carbamate (Boc), and carboxybenzyl carbamate (cbz).

The amide protecting group may include, for example, acetamide,phenylacetamide, 3-phenylpropanamide, pent-4-enamide, picolinamide,3-pyridylcarboxamide, benzamide, p-phenylbenzamide,2-methyl-2-(o-phenylazophenoxy)propanamide), 4-chlorobutanamide,acetoacetamide, 3-(p-hydroxyphenyl)propanamide), and(N′-dithiobenzyloxycarbonylamino)acetamide.

Examples of suitable protecting groups also include tert-butyl, benzyl,4-methoxybenzyl, benzyloxymethyl, phenacyl, allyl, trimethylsilyl,benzyloxycarbonyl, tert-butoxycarbonyl, and acetal and ketalderivatives. In some embodiments, R is selected from trityls,substituted trityls (e.g., monomethoxytrityl (MMTr), dimethoxytrityl(DMTr), trimethoxytrityl (TMTr), 2-chlorotrityl (CITr) andp-bromophenacyloxytrityl (BPTr), pixyls and substituted pixyls (see, forexample, U.S. Publication No. 2007/0276139). In some embodiments, R isselected from trityl, monoalkoxytrityl, dialkoxytrityl, pixyl,alkoxypixyl, fluorenylmethyloxycarbonyl, trifluoroacetyl, acetal, andcyclic acetal.

In some embodiments, R is a hydrophobic separation handle.

A hydrophobic separation handle is as described herein. In someembodiments, the hydrophobic separation handle is also a protectinggroup as described herein. In some embodiments, at least one of R and Gis a hydrophobic separation handle.

In some embodiments, only one of R and G is a hydrophobic separationhandle (e.g., a trityl group) as provided herein. For example, if R is ahydrophobic separation handle, then G is hydrogen or an alkoxy. In someembodiments, R is a protecting group and G is hydrogen or an alkoxy. Insome embodiments, R is absent and G is a trityloxy group. In someembodiments, the hydrophobic separation handle is a substituted orunsubstituted trityl or trityloxy group. For example, only one of R andG is a substituted or unsubstituted trityl or trityloxy group.

In some embodiments, R² is absent or is selected from the groupconsisting of: trityl, monoalkoxytrityl, dialkoxytrityl, pixyl,alkoxypixyl, fluorenylmethyloxycarbonyl, alkylcarboxyl, benzoyl,tetrahydropyranyl, and methyl.

A compound of formula (3) can be prepared, for example, by contacting amonosubstituted polymer comprising a linear, water-soluble, non-peptidicand non-nucleotidic polymer backbone bonded at the first terminus withthe functional group M²-R², with a reagent of formula (5):

wherein:

R⁵ and R⁶ independently from each other represent C₁-C₆-alkyl or R⁵ andR⁶ jointly form a 5- or 6-membered ring with the N to which they arebonded; under conditions facilitating the conversion of themonosubstituted polymer to a compound of formula (3).

In some embodiments, R⁵ and R⁶ are independently a C₁-C₆-alkyl. Forexample, R⁵ and R⁶ can be independently selected from the groupconsisting of methyl, ethyl, propyl, isopropyl, butyl, isobutyl,sec-butyl, tert-butyl, and hexyl. In some embodiments, R⁵ and R⁶ areisopropyl. In some embodiments, R⁵ and R⁶ jointly form a 5- or6-membered ring with the N to which they are bonded. For example, R⁵ andR⁶ jointly form a pyrrolidine, pyrroline, imidazoline, pyrazolidine,piperidine, 1,2,3,6-tetrahydropyridine, 1,4-dihydropyridine, piperazine,morpholine, thiomorpholine, pyridyl, pyrazinyl, pyrimidinyl,particularly 2- and 4-pyrimidinyl, pyridazinyl, pyrrolyl, particularly2-pyrrolyl, imidazolyl, thiazolyl, oxazolyl, and pyrazolyl, particularly3- and 5-pyrazolyl. In some embodiments, R⁵ and R⁶ jointly form amorpholine ring.

The ratio of a monosubstituted polymer to a reagent of formula (5) canrange from about 1:10 to about 10:1 (e.g., about 2:1, about 3:1, about4:1, about 5:1, about 6:1, about 7:1, about 8:1, about 9:1, about 1:2,about 1:3, about 1:4, about 1:5, about 1:6, about 1:7, about 1:81 about1:9, about 2:8, about 3:7, about 4:6 about 5:10, and about 4:8). In someembodiments, the ratio of a polymer to a reagent of formula (5) is fromabout 1:1 to about 1:10. In some embodiments, the ratio of a polymer toa reagent of formula (5) is about 2:1.

In some embodiments, the conversion of a monosubstituted polymer to acompound of formula (3) is quantitative.

In some embodiments, conditions that facilitate formation of a compoundof formula (3) include the addition of an activating reagent. Anactivating reagent is then added to the mixture of the monoderivatizedproduct and the reagent of formula (5) or (6). An activating reagent canbe any group suitable to initiate coupling of the polymer and thereagent of formula (5) or (6). Suitable activating reagents include, forexample, 1H-tetrazole, 5-(ethylthio)-1H-tetrazole (ETT),5-(benzylthio)-1H-tetrazole (BTT), Activator 42(5-(3,5-bis(trifluoromethyl)phenyl)-1H-tetrazole), 2-ethylthiotetrazole,2-bezylthiotetrazole, 4,5-dicyanoimidazoleand 4,5-dicyanoimidazole(DCI). In some embodiments, an activating agent can be selected frompyridinium hydrochloride, pyridinium trifluoroacetage, and bufferedcarboxylic acids.

In some embodiments, conditions that facilitate formation of a compoundof formula (3) include addition of an oxidizing agent to oxidize P⁺³ toP⁺⁵. Suitable oxidizing agents and conditions can be readily determinedby those of ordinary skill in the art. For example, an oxidant such asRuO₄ ⁻/NMO, Dess-Martin's reagent, DMSO/triflic anhydride, PDC, hydrogenperoxide, inorganic peroxides, nitric acid, nitrates, chlorite,chlorate, perchlorate, hypochlorite, peroxide, iodine, ozone, nitrousoxide, silver oxide, permanganate salts, hexavalent chromium compounds,chromic acid, dichromic acids, chromium trioxide, pyridiniumchlorochromate, persulfuric acid, sulfoxides, sulfuric acid, Tollens'reagent, 2,2′-dipyridiyldisulfide (DPS), and osmium tetroxide may beused.

In some embodiments, iodine can be used as an oxidizing agent. Forexample, a solution of iodine can be used and prepared by dissolvingiodine in a mixture of pyridine, tetrahydrofuran and water. Elementalsulfur can be used for phosphite oxidation combined with formation ofsulfurized product. In some embodiments, other more soluble and morereactive reagents, such as 3H-1,2-benzothiazol-3-one 1,1-dioxide(Beaucage reagent), phenylacetyl disulfide (PADS) or dimethylthiuram(DTD) can be used. Alternatively, peroxides exemplified by t-butylhydrogen peroxide or m-chlorobenzoyl peroxide may be used for P⁺³ to P⁺⁵oxidations.

In some embodiments, an oxidizing reagent is selected from a groupconsisting of: iodine, hydrogen peroxide, t-butyl hydrogen peroxide,acetone peroxide, sulfur, and thiuram disulfide.

In some embodiments, R and/or R¹ is a protecting group or a hydrophobicseparation handle. In some embodiments, the method can further includepurifying the monoderivatized compound using chromatography (e.g.,reverse phase chromatography). In some embodiments, the method furtherincludes removal of one or more of the protecting groups. In someembodiments, the method further includes removal of one or more of thehydrophobic separation handles.

For the methods provided above, the deprotection may involve, forexample, either sequential or one-pot deprotection of certain protectinggroups. Suitable reagents and conditions for the deprotection can bereadily determined by those of ordinary skill in the art. For example,deprotection may be achieved upon treatment of the protected compoundunder conditions so that hydroxyl protecting groups, such as acetate,isopropylidine, benzylidine, trityl, and pixyl protecting groups, areremoved from the protected compound. The acetate group can be cleavedunder mild conditions, for example, by diluted solution of ammonia or bysolution of potassium carbonate. The benzylidene and isopropylidenegroups can be cleaved by hydrogenation or using acidic hydrolysis asreported by R. M. Hann et al., J. Am. Chem. Soc., 72, 561 (1950). In yetanother example, the deprotection can be performed so that aminoprotecting groups, such as 9-fluorenylmethyl carbamate (Fmoc), t-butylcarbamate (Boc), and carboxybenzyl carbamate (cbz) protecting groups arecleaved from the protected compound. 9-fluorenylmethyl carbamate (FMOC)can be removed under mild conditions with an amine base (e.g.,piperidine) to afford the free amine and dibenzofulvene, as described byE. Atherton et al, “The Fluorenylmethoxycarbonyl Amino Protecting Group”in The Peptides, S. Udenfriend and J. Meienhofer, Academic Press, NewYork, 1987, p. 1. t-butyl carbamate (Boc) can be removed, as reported byG. L. Stahl et al., J. Org. Chem., 43, 2285 (1978), under acidicconditions (e.g., 3 M HCl in EtOAc). Hydrogenation can be used to cleavethe carboxybenzyl carbamate (cbz) protecting group as described by J.Meienhofer et al, Tetrahedron Lett., 29, 2983 (1988).

In some embodiments, deprotection may be performed under anaerobicconditions. The deprotection may also be performed at ambienttemperature or at temperatures of from about 20-60° C. (e.g., 25, 30,35, 40, 45, 50, or 55° C.).

In some embodiments, the method can also include isolating the compoundof formula (3) by precipitation or crystallization.

Non-limiting examples of linking groups for use in the compoundsprovided herein include:

Provided herein is a new type of functional, water-soluble polymer, notbelonging to the classes of polypeptides or nucleotides and containingthe structure of formula (1):

In this schematic picture of such a modified polymer, A is the point ofbonding to the terminus of the polymer backbone, E is an oxygen orsulfur atom, K is selected from the group consisting of alkylene,alkyleneoxyalkylene, or an oligomeric form of alkyleneoxyalkylene, G ishydrogen or is selected from the group consisting of an alkoxy and ahydrophobic separation handle, Z¹ and Z² can be oxygen or nitrogen, insuch way that both Z¹ and Z² may be oxygen, but when Z¹ is NH then Z² isoxygen, and when Z² is NH then Z¹ is oxygen, L is selected from thegroup consisting of a divalent radical of a nucleoside, linear alkylene,branched alkylene, alkyleneoxyalkylene, oligomeric form ofalkyleneoxyalkylene, arylene, and substituted arylene, M is a protectedgroup that when deprotected is reactive with a biologically activemolecule, a group reactive with a biologically active molecule, ordetectable functional group, R is a protecting group, activating group,hydrogen or absent. Thus the L-M-R fragment is linked to a terminus ofthe polymer via a phosphotriester, thiophosphotriester oramidophosphotriester group.

One characteristic of a compound provided herein is that the functionalgroup M, via the group L, is connected to the chain of the polymer via aphosphotriester group or amido phosphodiester, known also asphosphoramidate group. In addition, a derivatized polymer may exist bothin an oxy and a thio form. Non-limiting examples of such groups include:

An important class of polymers provided herein, polyethylene glycols(PEG), were previously used in the synthesis of phosphoramidites of theformula: DMTr-O-PEG-O—P(OCE)N(iPr)₂. These compounds were used fordirect coupling of PEG molecules to synthetic nucleic acids or to asurface of a solid phase. In all reactions, the reactive phosphoramiditegroup was present at the terminal of the polymer. A polymer substitutedwith a phosphoramidite group is, however, not a subject of the presentdisclosure, as the phosphorous atom in the phosphoramidite group is thepart of the reactive functionality and not a part of the linker as inthe compounds provided herein.

This formal distinction can have a deeper chemical importance. Aphosphoramidite group can be designed to work in a completely water-freeenvironment. Upon activation with certain protonating agents/activatorsa phosphoramidite group can become extremely reactive, and in thepresence of water, this reactive function can decompose instantaneously,making this function inappropriate for conjugation to biologicalmaterial in aqueous solution. Additionally, published PEGphosphoramidites can contain a specially designed, labile protectinggroup adjacent to the phosphorous atom to convert the intermediatephosphotriester to a phosphodiester. The present document is based, atleast in part, on the observation that phosphodiesters are unstable inaqueous biological media such as blood, plasma or cellular extracts, dueto the presence of phosphatases and phosphodiesterases. This canpreclude phosphodiester linkages as a linking group within a structureof a conjugate, as long as it is aimed for use in biological media. Thisdocument, contrary to the existing literature, and contrary to allnormal procedures, recommends keeping the phosphate in the form of aphosphotriester or in the form of its amide in order to gain stabilityof the linking group/conjugate.

Phosphotriester bonds are very rare in nature, existing in most of thecases as cyclic products of RNA transformations. As non-charged variantsof nucleotides they gained some attention from those who hoped that itcould be possible to use this form of nucleotides as predrugs, whichwould be transformed in vivo to the active phosphodiester forms.However, acyclic phosphotriesters, lacking specially designed internalfeatures facilitating deprotection, were found completely stable, bothchemically at the physiological pH range, and enzymatically in thepresence of the most active phosphate hydrolytic enzymes: McGuigan etal, Nucl. Acids Res. 1989, 17 (15), 6065-6075; Hecker and Erion, J. Med.Chem. 2008, 51, 2328-2345; Conrad et al. Chem. Bio. Interactions 1986,60, 57-65; and Fidanza et al, Methods in Molecular Biology 1994, 26,121-143. The proposed way of linking a functional group to the polymericmolecule can include combining chemistry typical for nucleic acids withchemistry of polymers and their conjugates. Moreover, this combinationcan be performed in a way to yield a product with distinctly bettercharacteristics than if this combination of chemistries would proceedfollowing the standard path.

This document also provides methods and materials for introducing of auseful separation handle on the derivatized polymer. This separationhandle can be introduced simultaneously with the functional group, sothe presence of the separation handle becomes an indicator of successfulintroduction of the reactive group. If chromatographic properties of aparticular separation handle are properly chosen, it is possible todiscriminate between non-derivatized, monoderivatized andmultiderivatized (e.g., bis-derivatized) polymers. Most of theseparation handles used herein introduce hydrophobic properties to thepolymer, as the preferred method for separation of the modified polymersis based on reverse-phase analytical and preparative chromatography. Thechoice of a proper separation handle comes from consideration of severalpractical aspects such as:

-   -   a) The hydrophobic separation handle can be removed from the        polymer after purification in order to liberate the group        reactive with a biologically active molecule and to avoid        uncontrolled hydrophobic interactions within the conjugate—or        more generally to avoid uncontrolled hydrophobic interactions        during the interaction of the conjugate with the biological        environment. This can preclude work with analogues of mPEG which        contain a long hydrophobic alkyl ether chain instead of a        methoxy group at one of the polymer termini. For the same        reason, protection of an amino group as long chain fatty acid        amides is not practical, as this group can be removed only under        very extreme conditions.    -   b) As most of polymers and functional groups lack chromophoric        properties, the chromatographic separation of polymers can be        difficult. It is, therefore, advantageous if the separation        handle introduces additionally some chromophore properties to        the polymer. This can make protection of a terminal hydroxyl or        thiol group by means of a long chain aliphatic fatty acid ester        less interesting.    -   c) Chemical stability of the hydrophobic separation handle can        be easy to control depending on an actual situation. This aspect        is related mostly to the stability of other functional groups        present in the derivatized polymer.    -   d) Chromatographic properties of the hydrophobic separation        handle, and hence the properties of the derivatized polymer, can        be easy to control by chemical modification of the hydrophobic        separation handle.    -   e) Since even relatively stable phosphotriester bonds are        slightly labile under high pH conditions, it can be preferred to        avoid hydrophobic separation handles that can only be removed        under such conditions.

Examples of hydrophobic separation handles that fulfill all thesecriteria belong to the group of acid labile protecting groups and areknown as trityls, substituted trityls (e.g., monomethoxytrityl (MMTr),dimethoxytrityl (DMTr), trimethoxytrityl (TMTr), andp-bromophenacyloxytrityl (BPTr), pixyls and substituted pixyls (see, forexample, U.S. Publication No. 2007/0276139). They are all acid labile,with distinct UV chromophore properties. Their acid stability can beeasily controlled by the presence of different electron donating orelectron withdrawing groups. Introduction of alkoxy chains of differentlength to the trityl structure is a convenient method for modificationof their hydrophobic properties. Most of the Examples presented hereinutilize, therefore, trityl groups both for protection of reactivefunctions and for introduction of an efficient separation handle. Thisshould not be seen as a limitation of this disclosure, as other groups,even those which do not fulfill all the above criteria, may be useful inthe present methodology as hydrophobic separation handles. Thus, ageneral description of a potential hydrophobic separation handleprovided herein is: a hydrophobic group that withstands the presence oftrivalent phosphorus present in a phosphoramidite or in an activatedH-phosphonate, and which can also be employed for chromatographicresolution of modified polymer from the unmodified starting material.

With a few exceptions, there are few limits on the type and character ofa functional group M. These exceptions appear in cases when thefunctional group is very sensitive to reducing conditions and becomesdestroyed by the trivalent phosphoramidite group, with concomitantoxidation of phosphorus to the pentavalent oxidation state. The azidogroup is an example of such a reactive function that cannot be convertedto the appropriate phosphoramidite. In fact, trivalent phosphorus oftriphenylphosphine is used as an efficient reagent for conversion of anazido group to an amine. The activated dithio group, for example, as ina dithiopyridyl group, is another example that belongs to this category,although simple dithiols could be successfully converted to anddelivered in the form of a phosphoramidites. Nevertheless, thisdisclosure presents also a variant of the above phosphoramidite methodthat omits the mentioned stability problem, and provides the ability toprepare polymers containing even an azido or activated dithio group.

This method is known as H-phosphonate methodology followed by oxidationof P⁺³ by carbon tetrachloride/amine, and is similar to thephosphoramidite method in the sense that the incoming reagent containsreactive P⁺³ phosphorus, and the phosphorus atom is oxidized during thereaction process to its pentavalent stage. The H-phosphonate methodologywill be described in more detail later on in this text.

Many groups reactive with a biologically active molecule of interestneed to be protected in order to exist within the structure ofphosphoramidite reagent. Examples include, without limitation, amino,aminoxy, hydrazo, hydroxyl, thio, certain fluorophores and carboxygroups. Some of these groups, like biotin, do not demand protection, butcan be used in a protected form to obtain some additional effects. Insome cases, trityl, substituted trityl, pixyl, and substituted pixyl canbe used as protecting groups. One reason for this choice of a protectinggroup is the possibility for simultaneous introduction of a protectinggroup that also can be used as a hydrophobic separation handle in areverse phase (RP) based chromatographic separation process. Ifseparation is not demanded, like in the case where the polymer has onlyone reactive terminus (e.g., when using mPEG as a polymer backbone), andincorporation of a phosphoramidite may be forced to completion, anyprotecting group can be used for protection of the group reactive with abiologically active molecule. In particular, trifluoroacetamido and FMOCgroups may be used for the protection of amino, aminoxy and hydrazogroups in such phosphoramidites.

The use of phosphoramidites containing a protected group, that whenunprotected is reactive with a biologically active molecule, having ahydrophobic protecting group for derivatization of polymers has a clearadvantage over other methods. For example, the starting polymer does nothave to be partially protected in order to obtain pure,monofunctionalized polymers. The methods work with fully unblockedpolymers and improved yield is obtained using an excess of such anon-expensive polymer (e.g., non-derivatized PEG) over the amidite. Onevalue of this method is in the fact that the formed mixture consistingof mono-, bis-, or multi-derivatized polymers can be efficientlyseparated from each other.

Certain functional groups do not offer a straightforward possibility forintroduction of a desired hydrophobic protecting group. To this groupbelong NHS-esters, most of the fluorophores, iodoacetamido and maleimidogroups. Amidites containing these functional groups are not optimal forderivatization of diol-polymers, since the separation of the reactionmixtures can be impossible.

In some cases, polymer diols can be easily converted to certainmonoprotected derivatives, and this protection can offer the possibilityfor using chromatography to obtain pure, temporarily blockedmonoderivatized polymers. Even here the separation can be based onhydrophobic interactions between a hydrophobic support and a polymerderivatized with a hydrophobic protecting group acting as a hydrophobicseparation handle. Examples of handles used for this purpose include,without limitation, substituted or unsubstituted tritylated hydroxyls,tritylated thiols, and tritylated amines. Introduction of a trityloxy orpixyloxy group onto the terminus of a polymer is straightforward asthese polymers usually contain free hydroxyl groups. Introduction of atritylthio group requires activation of the hydroxyl group by itsconversion to a mesylate, tosylate, or by substitution with a halogen.In some cases, this last alternative can be used, as its implementationin the form of a Velsmeier reaction can be economically attractive. Theactivated polymer can then react with tritylmercaptan as described byConolly and Rider in Nucleic Acids Res. 1985, 13, (12), 4485-4502. Apolymer substituted with a thiol group also can be obtained by any ofthe other described methodologies, and then the thio group can beselectively tritylated in an acidic environment, utilizing the muchhigher affinity of the thio group over hydroxyl to carbocations. Thereare two ways to obtain polymers protected on one site with a tritylatedamine group. A process is described for direct alkylation of tritylaminewith alkyl halides so this method could be used directly in analogy tothe above alkylation of tritylmercaptan. On the other hand anyappropriate method for partial amination like alkylation of thephthalimide, alkylation of the trifluoracetamide or a Mitsunobuprocedure can be applied for preparation of a monoamino polymer. Thisstarting material, even in unpurified form, can be used for obtainingthe tritylated amino polymer in a two-step process, starting withsilylation of all free hydroxyls in a pyridine solution. All mentionedtritylated or pixylated polymers can be preoperatively purified by RPchromatography to isolate the pure mono substituted polymer. Thedescribed earlier mono-protected polymer derivatives, made by reacting apolymer with a selected phosphoramidite, offer an interestingalternative as a mono-protected polymeric starting material foradditional derivatization. Such a polymer can react next with aphosphoramidite to incorporate another functional group, so the finalproduct can contain, for example, two separate phosphotriester linkages.

Monomethoxy PEG (mPEG), or generally monoalkylated polymers, can be usedfor the same purpose. Methoxy PEG'S are used to guaranteemonofunctionalization of a polymer. The problem is that such polymerscan be contaminated by an unknown and variable amount of bis hydroxyl(diol) polymer. In the case of PEG the existence of the diol form is aconsequence of moisture present during the polymerization of theethyleneoxide, and this can be hard to avoid on an industrial scale.Even the slightest amount of water can result in formation of a hydroxylanion—an undesired starting point of polymerization. Thus mPEG is not anoptimal polymer for preparation of pure monofunctionalized polymers.

Once a polymer is properly monoprotected, however, its conversion to areactive monofunctional derivative is straight-forward. Phosphoramiditechemistry allows incorporation of a reactive functionality with yieldand speed that is beyond the competition of other chemical processes,including all sorts of hydroxyl alkylation reactions. Using the properexcess of these reagents, the reported yields exceed 98% for every stepin a multistep process and are often nearly quantitative. In cases whereonly a single incorporation of a phosphoramidite takes place, thisreaction can be expected to be quantitative.

There exists also an interesting alternative process to the describedabove functionalization following the previously describedmonoprotection. Groups reactive with a biologically active molecule thatlack the possibility of carrying a hydrophobic separation handle can beincorporated into a trisubstituted unit having the reactive group ofchoice, the hydrophobic separation handle and the phosphoramidite group.There are several such units or molecules that can be used as carriers(scaffolds) for the construction of such trisubstituted block reagents.One of the simplest molecules, due to the ease of the chemicalmanipulations, is the uridine-based scaffold described by Hovinen andHakala in Organic Lett. 2001, 3(16) 2473-2476, where R denotes areactive group and L is an aliphatic linker to the uridine ring.

For instance, using reagents belonging to this category, it is possibleto prepare, in a single reaction step, polymers covalently bonded todifferent fluorescent functionalities that can be isolated as a monosubstituted polymeric product.

The chemistry of phosphoramidites is mostly associated with thechemistry of nucleic acids. The very high demands of this multistepprocess require rather large excess of incoming amidites, and efficientcatalysts. Examples of activators includes, without limitation,1H-tetrazole, 5-(ethylthio)-1H-tetrazole (ETT),5-(benzylthio)-1H-tetrazole (BTT), Activator 42(5-(3,5-bis(trifluoromethyl)phenyl)-1H-tetrazole), and4,5-dicyanoimidazole (DCI). Those are often expensive, and if applied tothe synthesis of polymers, as in this disclosure, they would noticeablyincrease the price of the final reagent. However, as the chemistry inthe present disclosure can have a single coupling step, and thequantitative yield of the reaction is not always necessary, it ispossible to use other less expensive catalysts. The use of pyridiniumhydrochloride or even buffered carboxylic acids for activation ofphosphoramidites is described and proved, offering high reaction rate,albeit with minimally lower coupling yield.

The choice of an oxidizing reagent is another factor for consideration.Iodine is the simplest alternative, as this reagent can be prepared bydissolving iodine in a mixture of pyridine, tetrahydrofuran and water.Elemental sulfur can be used for phosphite oxidation combined withformation of sulfurized product, but it can be poorly soluble in organicsolvents which can be used in the procedures described herein. Other,better soluble and more reactive reagents, like3H-1,2-benzothiazol-3-one 1,1-dioxide (Beaucage reagent), phenylacetyldisulfide (PADS) or dimethylthiuram (DTD) were developed for thispurpose. Thiophosphotriester linkages do not offer very much advantageover the normal phosphotriester linkages, as the latter can already besufficiently stable, but may offer additional possibilities, e.g. theability of chemical cleavage of this linkage. Peroxides exemplified byt-butyl hydrogen peroxide or m-chlorobenzoyl peroxide can be used asalternatives for P⁺³ to P⁺⁵ oxidations. They are colorless, can workunder water-free conditions and are often applicable in situations whereiodine promoted oxidations may lead to some unwanted side reactions.

It was mentioned earlier that groups reactive with a biologically activemolecule which do not tolerate a coexistence with the phosphoramiditegroup can be attached to the polymer by H-phosphonate chemistry. Thismethod takes advantage of the fact that P⁺³ of the H-phosphonate isactually tetracoordinated, and as such this group can be more stable foroxidation than a phosphate triester or phosphoramidite. The particularlyimportant point is that H-phosphonate does not interact with an azidogroup like most P⁺³ containing compounds. The use of this methodologyfor incorporation of the azido group can be, however, combined with theincorporation of a useful hydrophobic separation handle allowing fordiscrimination between the product and unreacted starting material.Application of a trifunctional reagent, similar to the mentioned uridinederivative, but using a H-phosphonate instead of a phosphoramiditegroup, could be an alternative. In this case, the activation of thestarting H-phosphonate reagent and its reaction with the polymer can befollowed by addition of an excess of an appropriate alcohol (e.g.,isopropanol) to convert the formed H-phosphonate diester to the desiredH-phosphonate triester. The Examples below describe a slightly differentprocedure. Here, the procedure of introducing an azido group and ahydrophobic separation handle has been divided into two steps, insteadof making it in a single step, using a trifunctional reagent. This isnot an optimal approach, but it was possible due to very high yield ofeach reaction. Polymer was first reacted with H-phosphonate oftritylated diethyleneglycol. It is important to use a starting glycolcontaining more than two carbons; otherwise, the free OH group in thefinal product, after removal of the trityl group, may destabilize thephosphotriester linkage. Oxidation of P⁺³ to P⁺⁵ was combined with theintroduction of the azido group into the polymer, and it was doneaccording to the described CCl₄/pyridine/amine procedure, usingl-amino-6-azidohexane as a source of the azido group. The opposite orderof incorporation of reactive groups using H-phosphonate chemistry isalso feasible. It is also recognized that H-phosphonate chemistry couldbe applied for the incorporation of any of existing reactive groups, ifother factors of interest like hydrolytic stability of the startingreagents, or costs of syntheses, are deciding.

Conjugates

This document also provides conjugates that include a compound hasprovided herein and a biologically active molecule. Preparation of suchconjugates occurs through a coupling reaction between the group reactivewith a biologically active molecule and the biologically activemolecule.

Examples of biologically active molecules include therapeutic agents,small molecules such as synthetic drugs, oligo- and polypeptides,oligonucleotides, coding DNA sequences, antisense DNA sequences, mRNAs,antisense RNA sequences, RNAis, and siRNAs, carbohydrates, lipids,growth factors, enzymes, transcription factors, toxins, antigenicpeptides (as for vaccines), antibodies, and antibody fragments.

Numerous other examples of biologically active molecules will beapparent to the skilled artisan.

Preparations

Also provided herein are preparations that include a compound orconjugate provided herein. In some embodiments, a preparation caninclude at least 50% of a compound or conjugate by weight. For example,a preparation can include at least 60%, at least 65%, at least 70%, atleast 75% at least 77%, at least 80%, at least 85%, at least 87%, atleast 89%, at least 90%, at least 92%, at least 94%, at least 95%, atleast 96%, at least 97%, at least 98%, and at least 99% by weight of thecompound or conjugate. In some embodiments, the compound or conjugate isessentially pure in the preparation.

A preparation can be a solution, a reaction mixture, a chromatographiceluent, a solid (e.g., a power or crystalline form of the preparation),or any other mixture that includes a compound or conjugate in theappropriate amount or level or purity.

Pharmaceutically Acceptable Salts and Compositions

This document also provides pharmaceutically acceptable salts of thecompounds and conjugates provided herein. Examples of pharmaceuticallyacceptable salts of a compound or a conjugate provided herein includeacid addition salts and base salts of the same.

Suitable acid addition salts are formed from acids which form non-toxicsalts. Examples include, without limitation, the acetate, adipate,aspartate, benzoate, besylate, bicarbonate/carbonate,bisulphate/sulphate, borate, camsylate, citrate, cyclamate, edisylate,esylate, formate, fumarate, gluceptate, gluconate, glucuronate,hexafluorophosphate, hibenzate, hydrochloride/chloride,hydrobromide/bromide, hydroiodide/iodide, hydrogen phosphate,isethionate, D- and L-lactate, malate, maleate, malonate, mesylate,methylsulphate, 2-napsylate, nicotinate, nitrate, orotate, oxalate,palmitate, pamoate, phosphate/hydrogen, phosphate/phosphate dihydrogen,pyroglutamate, saccharate, stearate, succinate, tannate, D- andL-tartrate, l-hydroxy-2-naphthoate tosylate, and xinafoate salts.

Suitable base salts are formed from bases which form non-toxic salts.Examples include, without limitation, the aluminium, arginine,benzathine, calcium, choline, diethylamine, diolamine, glycine, lysine,magnesium, meglumine, olamine, potassium, sodium, tromethamine, and zincsalts.

Hemisalts of acids and bases may also be formed, for example,hemisulphate and hemicalcium salts.

A conjugate, as provided herein, can be formulated into a pharmaceuticalcomposition that includes an effective amount of a conjugate and apharmaceutically acceptable excipient. Also provided herein arepharmaceutical compositions that includes an effective amount of acompound as provided herein, wherein M is a detectable functional group,and a pharmaceutically acceptable excipient.

Non-limiting examples of pharmaceutical excipients suitable foradministration of the conjugates and compounds provided herein includeany such carriers known to those skilled in the art to be suitable forthe particular mode of administration. Pharmaceutically acceptableexcipients include, but are not limited to, ion exchangers, alumina,aluminum stearate, lecithin, self-emulsifying drug delivery systems(SEDDS) such as d-α-tocopherol polyethylene glycol 1000 succinate,surfactants used in pharmaceutical dosage forms such as Tweens or othersimilar polymeric delivery matrices, serum proteins, such as human serumalbumin, buffer substances such as phosphates, glycine, sorbic acid,potassium sorbate, partial glyceride mixtures of saturated vegetablefatty acids, water, salts or electrolytes, such as protamine sulfate,disodium hydrogen phosphate, potassium hydrogen phosphate,sodium-chloride, zinc salts, colloidal silica, magnesium trisilicate,polyvinyl pyrrolidone, cellulose-based substances, polyethylene glycol,sodium carboxymethyl cellulose, polyacrylates, waxes,polyethylene-polyoxypropylene-block polymers, and wool fat.Cyclodextrins such as α-, β, and γ-cyclodextrin, or chemically modifiedderivatives such as hydroxyalkylcyclodextrins, including 2- and3-hydroxypropyl-b-cyclodextrins, or other solubilized derivatives canalso be advantageously used to enhance delivery of a compound orconjugate provided herein. In some embodiments, the excipient is aphysiologically acceptable saline solution.

A pharmaceutical composition can be, in one embodiment, formulated intosuitable pharmaceutical preparations such as solutions, suspensions,tablets, dispersible tablets, pills, capsules, powders, sustainedrelease formulations or elixirs, for oral administration or in sterilesolutions or suspensions for parenteral administration, as well astransdermal ointments, creams, gels, and patch preparations and drypowder inhalers (see, e.g., Ansel Introduction to Pharmaceutical DosageForms, Fourth Edition 1985, 126).

The concentration of a compound or conjugate in a pharmaceuticalcomposition will depend on absorption, inactivation, and excretion ratesof the compound or conjugate, the physicochemical characteristics of thecompound or conjugate, the dosage schedule, and amount administered aswell as other factors known to those of skill in the art.

The pharmaceutical composition may be administered at once, or may bedivided into a number of smaller doses to be administered at intervalsof time. It is understood that the precise dosage and duration oftreatment is a function of the disease being treated and may bedetermined empirically using known testing protocols or by extrapolationfrom in vivo or in vitro test data. It is to be noted thatconcentrations and dosage values may also vary with the severity of thecondition to be alleviated. It is to be further understood that for anyparticular patient, specific dosage regimens should be adjusted overtime according to the individual need and the professional judgment ofthe person administering or supervising the administration of thecompositions, and that the concentration ranges set forth herein areexemplary only and are not intended to limit the scope or practice ofthe claimed compositions.

The pharmaceutical compositions are provided for administration tohumans and animals in unit dosage forms, such as tablets, capsules,pills, powders, granules, sterile parenteral solutions or suspensions,and oral solutions or suspensions, and oil-water emulsions containingsuitable quantities of the compounds or conjugates. The pharmaceuticallytherapeutically active compounds or conjugates are, in one embodiment,formulated and administered in unit-dosage forms or multiple-dosageforms. Unit-dose forms as used herein refers to physically discreteunits suitable for human and animal patients and packaged individuallyas is known in the art. Each unit-dose contains a predetermined quantityof the therapeutically active compound or conjugate sufficient toproduce the desired therapeutic effect, in association with the requiredpharmaceutical carrier, vehicle or diluent. Examples of unit-dose formsinclude ampoules and syringes and individually packaged tablets orcapsules. Unit-dose forms may be administered in fractions or multiplesthereof. A multiple-dose form is a plurality of identical unit-dosageforms packaged in a single container to be administered in segregatedunit-dose form. Examples of multiple-dose forms include vials, bottlesof tablets or capsules or bottles of pints or gallons. Hence, multipledose form is a multiple of unit-doses which are not segregated inpackaging.

Liquid pharmaceutically administrable compositions can, for example, beprepared by dissolving, dispersing, or otherwise mixing a compound orconjugate as provided herein and optional pharmaceutical adjuvants in acarrier, such as, for example, water, saline, aqueous dextrose,glycerol, glycols, ethanol, and the like, to thereby form a solution orsuspension. If desired, a pharmaceutical composition to be administeredmay also contain minor amounts of nontoxic auxiliary substances such aswetting agents, emulsifying agents, solubilizing agents, pH bufferingagents and the like, for example, acetate, sodium citrate, cyclodextrinederivatives, sorbitan monolaurate, triethanolamine sodium acetate,triethanolamine oleate, and other such agents.

Dosage forms or compositions containing a compound or conjugate providedherein in the range of 0.005% to 100% with the balance made up fromnon-toxic carrier may be prepared. Methods for preparation of thesecompositions are known to those skilled in the art. The contemplatedcompositions may contain 0.001%-100% active ingredient, in oneembodiment 0.1-95%, in another embodiment 75-85%.

Pharmaceutical compositions suitable for the delivery of a compound orconjugate provided herein and methods for their preparation will bereadily apparent to those skilled in the art. Such compositions andmethods for their preparation may be found, for example, in Remington'sPharmaceutical Sciences, 19th Edition (Mack Publishing Company, 1995).

Synthesis

Compounds and conjugates provided herein, including salts thereof, canbe prepared using known organic synthesis techniques and can besynthesized according to any of numerous possible synthetic routes. Insome embodiments, a compound or conjugate is prepared using a method asprovided herein.

The reactions for preparing compounds and conjugates provided herein canbe carried out in suitable solvents which can be readily selected by oneof skill in the art of organic synthesis. Suitable solvents can besubstantially non-reactive with the starting materials (reactants), theintermediates, or products at the temperatures at which the reactionsare carried out, e.g., temperatures which can range from the solvent'sfreezing temperature to the solvent's boiling temperature. A givenreaction can be carried out in one solvent or a mixture of more than onesolvent. Depending on the particular reaction step, suitable solventsfor a particular reaction step can be selected by the skilled artisan.

Preparation of compounds can involve the protection and deprotection ofvarious chemical groups. The need for protection and deprotection, andthe selection of appropriate protecting groups, can be readilydetermined by one skilled in the art. The chemistry of protecting groupscan be found, for example, in Protecting Group Chemistry, 1^(st) Ed.,Oxford University Press, 2000; March's Advanced Organic chemistry;Reactions, Mechanisms, and Structure, 5^(th) Ed., Wiley-IntersciencePublication, 2001; and Peturssion, S. et al, “Protecting Groups inCarbohydrate Chemistry” J. Chem. Educ., 74(11), 1297 (1997) (each ofwhich is incorporated herein by reference in their entirety.

Reactions can be monitored according to any suitable method known in theart. For example, product formation can be monitored by spectroscopicmeans, such as nuclear magnetic resonance spectroscopy (e.g., ¹H or¹³C), infrared spectroscopy, spectrophotometry (e.g., UV-visible), massspectrometry, or by chromatographic methods such as high performanceliquid chromatography (HPLC), liquid chromatography-mass spectroscopy(LCMS) or thin layer chromatography (TLC). Compounds can be purified bythose skilled in the art by a variety of methods, including highperformance liquid chromatography (HPLC) (“Preparative LC-MSPurification; Improved Compound Specific Method Optimization” K. F.Blom, et al, J. Combi. Chem. 6(6) (2004), which is incorporated hereinby reference in its entirety) and normal phase silica chromatography.

EXAMPLES Example 1

Synthesis of isopropyl phosphorodichloridite was performed according tothe modified literature procedure of Zwierzak and Koziara, Tetrahedron(1967), 23, 2243-2252.

Dry isopropanol (2 mole) in 100 mL of dry diethyl ether was addeddropwise to the vigorously stirred mixture of phosphorus trichloride (4mole) in 200 mL of diethyl ether at −20° C. The mixture was allowed towarm up to room temperature, and was stirred at this temperature for 4hours. The mixture was fractionally distilled at normal pressure toobtain the title product by collecting a colorless fraction having bp.120-125° C.

Example 2 Synthesis of isopropyl, N,N-diisopropylphosphoramidochloridite

Isopropyl phosphorodichloridite (56.5 g, 0.5 mole) in dry diethyl ether(300 mL) was placed in a 1 L round bottom flask and cooled to −30° C. Tothis vigorously stirred solution, dry diisopropyl amine (109 g, 1 mole)in diethyl ether (200 mL) was added dropwise (2 hr) at the above lowtemperature. The mixture was then allowed to warm to room temperatureand was left at this temperature overnight. The thick white cake ofdiisopropylammonium hydrochloride was filtered off on a large filterfunnel and washed with two portions of ether. The combined ether phasewas evaporated and the residue was distilled at lowered pressurecollecting a fraction boiling at 83-85° C. (15 Torr).

Example 3

The following is a general procedure used to prepare differentphosphoramidite reagents.

An appropriately protected alcohol (1 eq) was placed in a round bottomflask and dried by coevaporation with toluene. The residue was dissolvedin dry dichloromethane (DCM) (5 mL/mmole), and dry triethylamine (TEA)(4 eq) was added in one portion. To this solution, stirred at roomtemperature, isopropyl, N,N-diisopropylphosphoramidochloridite (1.5 eq)in DCM (2 mL/mmole) was added dropwise. The mixture was stirred anadditional 30 minutes and when TLC (DCM:Methanol:TEA 95:4:1) showed acomplete consumption of the starting alcohol, methanol (5 eq) was addedin one portion and the mixture was stirred further for 30 minutes. Thereaction mixture was partitioned between dichloromethane and an aqueoussolution of sodium bicarbonate. The organic extracts were combined,evaporated, dried by coevaporation with toluene, and purified by flashcolumn chromatography on silica gel using a gradient of ethyl acetate inhexane with addition of 2% TEA as an eluent. The appropriate fractionswere collected, and evaporated. The residual solvents were removed underhigh vacuum, yielding products in the form of thick oils.

The following starting alcohols were prepared according to the publishedliterature and converted to the respective isopropyl phosphoramiditesusing the procedure outlined above:

1) An amidite useful for introduction of an amino group was prepared bymodification of the method of Gaur, Nucleosides, Nucleotides & NucleicAcids (1991), 10, (4), 895-909:

2) An amidite useful for introduction of an aminoxy group was preparedin a process similar to the synthesis of described above for aminatingan amidite. The starting aminoxy alcohol was prepared from 6-bromhexanolaccording to Khomutov, Zhurnal Obshch Khimyi 1961, 31, 1992-1995:

3) An amidite useful for introduction of a hydrazo group was preparedusing a modified method of Raddetz et al., Nucleic Acids Res. 30, (21),4793-4802:

4) An amidite useful for introduction of a thiol was obtained followingthe procedure described by Connolly and Rider in Nucleic Acids Res.1985, 13, (12), 4485-4502:

5) An amidite useful for introduction of a carboxyl group was preparedutilizing a chlorotrityl group for protection of a carboxyl group as wasdescribed by Kachalova et al. Helv. Chim. Acta 2002, 85, 2409-2416:

6) An amidite useful for introduction of biotin was prepared followingthe methodology described by Krempsky et al., Tet. Lett., (1996), 37,(12), 4313-4316:

7) The following amidite, prepared in a method analogous to onedescribed by Singh et al. J. Org. Chem. 2004, 69, 8544-8546, was usedfor incorporation of an aliphatic aldehyde group. The aldehyde (as anamide of glyoxalic acid) was obtained after oxidative cleavage of thecis-amine alcohol group:

8) The following amidite can be used for incorporation of an aliphaticaldehyde group. This reagent was made in analogy to Spinelli et al.Nucleosides, Nucleotides and Nucleic Acids 2007, 26, 883-887. Thealdehyde was obtained after acidic hydrolysis of the acetal bond andoxidation of the cis diol system:

9) The following amidite, prepared by modification of method ofPodyminogin et al., Nucl. Acids Res. 2001, 29, (24), 5090-5098, can beused for incorporation of an aromatic aldehyde group:

10) An amidite allowing for introduction of an active ester in a singlechemical step was prepared analogously to the method described in U.S.Pat. No. 6,320,041:

Example 4

The following is a general procedure that was used for the synthesis ofpure monosubstituted PEG polymers.

This method utilizes non-derivatized PEG used in excess over theselected phosphoramidite reagent in order to obtain better selectivity.Amidites containing a hydrophobic moiety, like trityl, substitutedtrityl, long chain fatty esters, or acetals introduce a separationhandle that can be used for reversed-phase based chromatographicseparation of the product.

Thus PEG 6000 (60 g, 10 mmole, 2 eq.) was dried by double coevaporationwith toluene (heating was applied in order to dissolve all material).The residue was dissolved in dry acetonitrile (50 mL) and an appropriatephosphoramidite (5 mmole, 1 eq.) in dry acetonitrile (30 mL) was addedin one portion. To this clear solution, stirred at room temperature, asolution of 4,5-dicyanoimidazole (5.9 g, 50 mmol, 10 eq.) inacetonitrile was added in a single portion and the mixture was stirredfor 15 minutes. Reaction was stopped by addition of a solution of iodine(0.1 M, 1.2 eq) in THF:pyridine: water (10:10:1) and the brownishsolution was stirred for 3 minutes. Aqueous solution of sodium bisulfitewas added in small portions until decolorization of the reactionmixture. After evaporation of most of the volatile matter, the residuewas dissolved in dichloromethane and extracted with a saturated aqueoussolution of sodium bicarbonate. The evaporated organic phase was driedby coevaporation with toluene, and the residue was crystallized fromisopropanol. The isolated crystals were dissolved in a small amount ofdichloromethane and precipitated by addition of diethyl ether. The finalmixture, being a composition containing a free non-derivatized PEG,mono- and bis-derivatized PEG, was preperatively purified byreverse-phase chromatography. Fractions containing the desired productwere evaporated, dried and precipitated from diethyl ether. When removalof the acid labile separation handle was required the polymer isdissolved in isopropanol (with slight heating) and a 5% solution oftrichloracetic acid in isopropanol was added. The mixture is cooled downin the freezer to obtain a deprotected crystalline product. If a TLCtest (silicagel plates in 10% MeOH:DCM) for the purity of the productstill showed the presence of the trityl protecting group, the procedureof acidic deprotection was repeated. Deprotection of otherfunctionalities were performed following the literature procedures asfar as was possible, but with some modifications:

1) Trityl protected thiol modified polymer was deprotected with a silvernitrate solution in water. After 30 minutes the solution was treatedwith dithiotreithiol (2 eq. to the amount of silver ions added) and thepH was raised to 9.0 by addition of potassium carbonate. After 30minutes, the mixture was filtered through a pad of celite and extractedby dichloromethane. The organic phase was evaporated and thiolated PEGwas crystallized from isopropanol.

2) Polymers modified with different aldehyde-introducingphosphoramidites were first treated with acid to remove the trityl orthe acetal function. In the case of reagent 7 (Example 3) the FMOC groupwas removed by treatment of the polymer with 10% piperidine in DCM for 4hours, followed by quick evaporation of the volatile matter andcrystallization of the residue from isopropanol. The final conversion ofthe cis-amino alcohol or cis-diol to the aldehyde was done by means of10 mM sodium periodate.

Example 5

Pure, mono-substituted PEG molecules used for further derivatizationwere prepared as follows.

Certain PEG derivatives can be prepared in a large scale and atreasonably low cost. These derivatives can be regarded by themselves asvaluable modifications, but also as a good monovalent starting material,well suited for further derivatization. This Example provides for thepreparation of three such derivatives:

1) Mono DMTr-O-Substituted, Linear PEG.

An appropriate PEG (100 g, 2 eq) was dried by double coevaporation withdry pyridine, dissolved in pyridine (100 mL), and DMTrCl (1 eq) wasadded to the stirred mixture at room temperature. The yellow solutionwas stirred for 24 hours and methanol (10 mL) was added. The reactionmixture was stirred for an additional 60 minutes, evaporated, dissolvedin dichloromethane, and treated with an aqueous solution of sodiumbicarbonate. The organic phase was evaporated, dried by coevaporationwith toluene, and all PEG was isolated after precipitation from diethylether. The collected mixture of PEG'S was purified by reverse-phasechromatography.

2) Mono MMTr-NH-Substituted, Linear PEG.

A commercial monoamino substituted PEG (1 eq) or a material preparedaccording to any of existing procedures, was dried by doublecoevaporation with dry pyridine. The residue was dissolved in pyridine(10 mL/mmole of PEG) and trimethylchlorosilane (TMSCl) (4 eq) was added.The mixture was stirred at room temperature for 4 hours and MMTrCl (1.5eq) was added. The reaction mixture was stirred overnight, and thenmethanol (50 eq) was added and the mixture was stirred for an additionaltwo hours. The total PEG was isolated after evaporation, drying bycoevaporation with toluene, crystallization from isopropanol andprecipitation from diethylether. The collected mixture of PEG's waspurified by reverse-phase chromatography.

3) Mono Tr-S-Substituted, Linear PEG.

An appropriate, non-derivatized PEG was dried by coevaporation withtoluene and dissolved in dry DMF (5 mL/mmole). To this stirred solutionat room temperature a preformed solution of phosphor oxychloride (0.4eq) in dry DMF (5 mL/mmole) was added and stirring was continued for 6hours. Most of the solvent was then evaporated, and the residue wastreated using a saturated aqueous sodium bicarbonate solution.Polyethylene glycol was extracted with dichloromethane and concentratedby evaporation of all volatile matter. The reaction mixture, containingthe monochloro-derivatized PEG was dissolved in ethanol (10 mL/mmole).Triphenylmethyl mercaptan (1.3 eq. to the starting PEG) was suspended inethanol (10 mL/mmole) and converted to the sodium salt by addition of anequivalent amount of sodium hydroxide dissolved in a small amount ofwater. The salt was combined with the ethanolic solution of PEG and themixture was stirred overnight. After evaporation of ethanol, the residuewas partitioned between dichloromethane and aqueous sodium bicarbonate.The organic phase was evaporated and the residue was crystallized fromisopropanol, followed by precipitation of total PEG from diethyl ether.The collected mixture of PEG's was purified by reverse-phasechromatography.

Example 6

-   -   a) Conversion of mono substituted PEG to bis-derivatized PEG was        performed using the following method.

A one equivalent of commercial methyl PEG (mPEG), (or any of partiallyprotected PEG's from the Examples 4 or 5), was dried by coevaporationwith toluene, and the polymer was dissolved in dry acetonitrile (5mL/mmole). The modifying phosphoramidite (2-3 eq.) in dry acetonitrile(3 mL/mmole) was added, followed by a suitable activator (10-15 eq.) andthe reaction mixture was stirred at RT for 15 minutes.

At this point all reactions were analyzed by fast reversed-phaseanalytical chromatography that showed disappearance of all startingmaterial and formation of more hydrophobic product. Reaction wasquenched by addition of an oxidizing iodine solution (1.5 eq. to theamount of the phosphoramidite) or t-butylhydrogenperoxide (4 eq to theamount of the phosphoramidite) in cases when the synthesized product didnot tolerate iodine or water. The iodine-treated reaction mixtures wereevaporated, dissolved in dichloromethane, decolorized with bisulfite,and the organic phase was evaporated. The t-butylhydrogenperoxidetreated mixtures were evaporated directly. Both mixtures were partiallypurified by crystallization from isopropanol, followed by precipitationfrom diethyl ether to obtain a pure, mono-functionalized,bis-substituted PEG. An azeotropically dried PEG was dissolved in dryacetonitrile (5 mL/mmole). The modifying phosphoramidite (1.0 eq.) indry acetonitrile (3 mL/mmole) was added, followed by a suitableactivator (10-15 eq.) and the reaction mixture was stirred at RT for 30minutes. Reaction was quenched by addition of an oxidizing iodinesolution (1.5 eq. to the amount of the phosphoramidite) or t-butylhydrogenperoxide (4 eq to the amount of the phosphoramidite) in caseswhen the synthesized product did not tolerate iodine or water. Theiodine-treated reaction mixtures were evaporated, dissolved indichloromethane, decolorized with bisulfite, and the organic phase wasevaporated. The t-butylhydrogenperoxide treated mixtures were evaporateddirectly. Both mixtures were partially purified by crystallization fromisopropanol, followed by precipitation from diethyl ether to obtainreaction mixture free of low molecular components. This mixture wasseparated on an analytical and on a preparative RP chromatographicsystem which allow for isolation of pure mono substituted product. Thismethodology could be easy applied for amidites introducing amino,hydroxylamino, hydrazo, carboxyl, aldehyde and the biotin group. Theisolated products could be deprotected upon treatment with appropriateacidic conditions, followed by precipitation of the deprotected PEG fromdiethylether, or the non-deprotected material could be used inpreparation of hetero-bis-functionalized polymer as presented bellow.

-   -   c) Using the above idea of conversion of PEG diol into a pure,        mono-functionalized product from Example 6 b) with subsequent        derivatization with another reagent, the following compounds        were prepared.    -   1)        MMTr-NH—(CH₂)₅—O—PO—(O-iPr)O-PEG-O(O-iPr)-PO—O—(CH₂)₆—O—NH-MMTr    -   2)        MMTr-NH—(CH₂)₅—O—PO—(O-iPr)O-PEG-O(O-iPr)-PO—O—CH(CH₃)(CH₂)₂—COO—ClTr.

The second derivatization were performed as in Example 6a) using excessof the second reagent over PEG to insure quantitative conversion to thedouble functionalized product The final compound was analyzed by HPLC,but any preparative chromatography at this stage was not needed.

Example 7

The following describes methods used to introduction functional groupswhich were not stable in the presence of the phosphoramidite group.

Diethylene glycol protected on one end with a DMTr group, and containinga IT-phosphonate group at the other end, was synthesized from atritylated diol by a standard PCl₃/triazole method according to Garegget al, Chem. Scr. 1986, 26, 59-62.

The above H-phosphonate (3 eq) and mPEG (1 eq) were dried by repeatedcoevaporation with dry pyridine. The residue was dissolved in pyridine(10 mL/mmole) and treated with pivaloyl chloride (9 eq). The mixture wasstirred at room temperature for 2 hours and the reaction was quenched byaddition of triethylammonium bicarbonate (TEAB) (1 M, 5 mL/mmole). Thereaction mixture was concentrated and partitioned betweendichloromethane and diluted TEAB. The organic phase was evaporated, theresidue was dried by repeated coevaporation with toluene, and total PEGwas purified by precipitation from diethyl ether. The isolatedprecipitate was filtered, dissolved in pyridine/carbon tetrachloride 2:1and 1-amino-6-azidohexane (4 eq.) was added. The stirred mixture wasleft overnight at room temperature. The mixture was evaporated,coevaporated with water, and the residual material was treated with anaqueous ammonia solution (25%, 20 mL/mmole) for 4 hours at roomtemperature in order to cleave the residual non-oxidized H-phosphonatedimer. Ammonia was evaporated and the resulting crude product waspurified by means of preparative reverse-phase chromatography. Finalremoval of the DMTr group and precipitation of the PEG gave the pureazido modified product.

-   -   1) An essentially pure, modified polymer, comprising a water        soluble, non peptidic and non nucleotidic, linear or branched        polymer backbone, containing from 2 and up to 100 termini, and        having at least one terminus being covalently bonded to the        structure:

-   -   wherein:        -   A is the point of bonding to the terminus of the polymer            backbone;        -   E is oxygen or sulfur;        -   K is selected from the group consisting of linear alkyl,            branched alkyl, alkyloxyalkyl, or oligomeric form of            alkyloxyalkyl;        -   G is none, or is selected from the group consisting of an            alkoxy, trityloxy or substituted trityloxy group;        -   Z₁ and Z₂ are O or NH in such a way that both Z₁ and Z₂ may            be O, but when Z₁ is NH then Z₂ is O, and when Z₂ is NH then            Z₁ is O.        -   L is selected from the group consisting of linear alkyl,            branched alkyl, nucleoside, alkyloxyalkyl, oligomeric form            of alkyloxyalkyl, aryl and substituted aryl;        -   M is a group reactive with a biologically active molecule or            detectable functional group;        -   R is selected from a group consisting of protecting groups,            hydrophobic separation handles, activating groups, hydrogen            or none, R₁ is a hydrophobic separation handle or none, and            both R and R₁ can coexist providing that there is only one            hydrophobic separation handle within the molecule or the            hydrophobicity of either of these groups is substantially            higher than the other;    -   2) The modified polymer of paragraph 1), wherein the functional        group M is selected from the group consisting of hydroxyl,        amine, thiol, carboxyl, aldehyde, glyoxal, dione, alkenyl,        alkynyl, alkedienyl, azide, acrylamide, vinyl sulfone,        hydrazide, aminoxy, maleimide, dithiopyridine, iodoacetamide,        biotin or a fluorophore.    -   3) The modified polymer of paragraph 1), wherein the group K is        selected from the group consisting of methyl, ethyl, propyl,        isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, hexyl, or a        residue from diethylene glycol, triethylene glycol,        tetraethylene glycol or hexaethylene glycol.    -   4) The modified polymer of paragraph 1), wherein the group L is        C₁-C₁₂ alkyl or substituted alkyl.    -   5) The modified polymer of paragraph 1), wherein the group R is        selected from trityl, monoalkoxytrityl, dialkoxytrityl, pixyl,        alkoxypixyl, FMOC, trifluoroacetyl, acetal, cyclic acetal or        combinations thereof.    -   6) The modified polymer of paragraph 1), wherein, for the        functional group M being carboxyl, the group R is selected from        the group consisting of chlorotrityl, trityl,        N-hydroxysuccinimidyl, p-nitrophenyl, pentachlorophenyl, simple        non-activating alkyls selected from the group of C₁-C₁₈ alkyls        or none.    -   7) The modified polymer of paragraph 1), wherein the non        peptidic and non nucleotidic polymer backbone is selected from        the group consisting of poly(alkylene glycol), poly(oxyethylated        polyol), poly(olefinic alcohol), poly(α-hydroxy acid),        poly(vinyl alcohol), polyoxazoline, and copolymers and mixtures        thereof.    -   8) The modified polymer of paragraph 1), wherein the non        peptidic and non nucleotidic polymer backbone is polyethylene        glycol).    -   9) The modified polymer of paragraph 8), wherein the        poly(ethylene glycol) has an average molecular weight from about        500 Da to about 100000 Da.    -   10) An essentially pure, linear form of modified polymer of        paragraph 1), wherein the two termini of the polymer are        modified non-symmetrically with two different functional groups        and wherein the two functional groups are linked to the polymer        as in the structure:

-   -   wherein:        -   M and M₁ are two different functional groups reactive with a            biologically active molecule or detectable functional            groups;    -   E and E₁ are independently oxygen or sulfur;        -   The pair Z₁ and Z₂ are independent from the pair Z₃ and Z₄            and both Z₁ and Z₂ may be O, but when Z₁ is NH then Z₂ is O,            and when Z₂ is NH then Z₁ is O, similarly for a pair of Z₃            and Z₄—both Z₃ and Z₄ may be O, but when Z₃ is NH then Z₄ is            O, and when Z₄ is NH then Z₃ is O;        -   L and L₁ are independently selected from the group            consisting of linear alkyl, branched alkyl, alkyloxyalkyl,            oligomeric form of alkyloxyalkyl, aryl and substituted aryl;        -   R and R₁ are independently protecting groups, activating            groups or none;        -   K and K₁ are independently selected from the group            consisting of linear alkyl, branched alkyl, alkyloxyalkyl,            or oligomeric form of alkyloxyalkyl;        -   G and G₁ are independently selected from the group            consisting of none, an alkoxy, trityloxy or substituted            trityloxy group;        -   L-M-R and L₁-M₁-R₁ fragments are linked to the respective            terminus of the said polymer via phosphotriester,            thiophosphotriester or amidophosphotriester bonds;    -   11) The modified polymer of paragraph 10), wherein the two        different functional groups M and M₁ are selected independently        from the group consisting of hydroxyl, amine, thiol, carboxyl,        aldehyde, glyoxal, dione, alkenyl, alkynyl, alkedienyl, azide,        acrylamide, vinyl sulfone, hydrazide, aminoxy, maleimide,        dithiopyridine, iodoacetamide, biotin or a fluorophore.    -   12) The modified polymer of paragraph 10), wherein the group K        is selected from the group consisting of methyl, ethyl, propyl,        isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, hexyl, or a        residue from diethylene glycol, triethylene glycol,        tetraethylene glycol or hexaethylene glycol.    -   13) The modified polymer of paragraph 10), wherein the group L        is C₁-C₁₂ alkyl or substituted alkyl.    -   14) The modified polymer of paragraph 10), wherein the group R        is selected from trityl, monoalkoxytrityl, dialkoxytrityl,        pixyl, alkoxypixyl, FMOC, trifluoroacetyl, acetal, cyclic acetal        or combinations of thereof.    -   15) The modified polymer of paragraph 10), wherein, for the        functional group M being carboxyl, the group R is selected from        the group consisting of chlorotrityl, trityl,        N-hydroxysuccinimidyl, p-nitrophenyl, pentachlorophenyl, simple        non-activating alkyls selected from the group of C₁-C₁₈ alkyls        or none.    -   16) The modified polymer of paragraph 10), wherein the polymer        is polyethylene glycol).    -   17) The modified polymer of paragraph 16), wherein the        poly(ethylene glycol) has an average molecular weight from about        500 Da to about 100000 Da.    -   18) An essentially pure, linear form of modified polymer of        paragraph 1), wherein the two termini of the polymer are        modified non-symmetrically with two different functional groups        and wherein the two functional groups are linked to the polymer        as in the structure:

-   -   wherein:        -   M and M₂ are two different functional groups reactive with a            biologically active molecules or M is a detectable            functional group;        -   E is O or S;        -   K is selected from the group consisting of linear alkyl,            branched alkyl, alkyloxyalkyl, or oligomeric form of            alkyloxyalkyl;        -   G is none or is selected from the group consisting of an            alkoxy, trityloxy, monoalkoxy substituted trityloxy group or            dialkoxy substituted trityloxy group;        -   Z₁ and Z₂ are O or NH in such way that both Z₁ and Z₂ may be            O, but when Z₁ is NH then Z₂ is O, and when Z₂ is NH then Z₁            is O;        -   L is selected from the group consisting of linear alkyl,            branched alkyl, alkyloxyalkyl, oligomeric form of            alkyloxyalkyl, aryl and substituted aryl;        -   R is a protecting group, activating group, hydrogen or none;            L-M-R fragment is linked to the first terminus of the said            polymer via phosphotriester, thiophosphtriester or            amidophosphotriester;        -   M₂ is O, S or NH;        -   M₂ is linked directly to the second terminus of the polymer,            and not via phosphotriester, thiophosphtriester or            amidophosphotriester;        -   R₂ is a protecting group or none.    -   19) The modified polymer of paragraph 18), wherein the        functional group M is selected from the group consisting of        hydroxyl, amine, thiol, carboxyl, aldehyde, glyoxal, dione,        alkenyl, alkynyl, alkedienyl, azide, acrylamide, vinyl sulfone,        hydrazide, aminoxy, maleimide, dithiopyridine, iodoacetamide or        biotin.    -   20) The modified polymer of paragraph 18), wherein the group R₂        is selected from the group consisting of trityl,        monoalkoxytrityl, dialkoxytrityl, pixyl, alkoxypixyl, FMOC,        alkylcarboxyl, benzoyl, tetrahydropyranyl, methyl or none.    -   21) The modified polymer of paragraph 18), wherein the polymer        is polyethylene glycol).    -   22) The conjugate of any polymer of paragraph 1) to 18) with a        biologically active molecule wherein said biologically active        molecule is selected from the group consisting of enzymes,        peptides, polypeptides, nucleotides, oligonucleotides,        polynucleotides and low molecular weight drugs.    -   23) A method of synthesizing a substantially pure, water soluble        polymer of paragraph 1), said method comprising the steps of:        -   a) contacting the water soluble polymer, of non-peptidic and            non-nucleotidic type, and having linear or branched polymer            backbone, and containing from 2 and up to 100 termini, in a            water free solvent, with a selected modifying reagent in            form of the phosphoramidite derivative as in the structure:

-   -   -   -   wherein:            -   R₃ and R₄ are isopropyls or are a part of morpholine                ring.

        -   b) starting reaction by addition of an activating reagent.

        -   c) oxidation of P⁺³ to P⁺⁵ by addition of an oxidizing            reagent.

        -   d) optional chromatographic purification of the protected            polymer.

        -   e) removal of the protecting groups.

    -   24) Method of paragraph 23) wherein the activating reagent is        selected from tetrazole, 2-ethylthiotetrazole,        2-bezylthiotetrazole, 4,5-dicyanoimidazole, “Activator 42”,        pyridinium hydrochloride or pyridinium trifluoroacetate

    -   25) Method of paragraph 23) wherein the oxidizing reagent is        selected from a group consisting of iodine, water peroxide,        t-butyl hydrogen peroxide, acetone peroxide, sulfur and thiuram        disulfide.

    -   26) Method of paragraph 23), wherein the ratio between the        polymer and the phosphoramidite is from 1:1 to 10:1 in order to        facilitate formation of monosubstituted product.

    -   27) A method of synthesizing a substantially pure, water soluble        polymer of paragraph 10), said method comprising the steps of:        -   a) reacting the water soluble polymer, of non-peptidic and            non-nucleotidic type, having linear polymer backbone, and            containing two reactive termini, in a water free solvent,            with a selected first modifying reagent in form of the            phosphoramidite derivative, under conditions that facilitate            formation of monoderivatized product.        -   b) chromatographic isolation of the monoderivatized polymer.        -   c) reacting the monoderivatized product with a second            modifying reagent in the form of phosphoramidite derivative,            under conditions that facilitate the quantitative conversion            to the double modified polymer.        -   d) isolation of the double modified polymer by precipitation            or crystallization.

    -   28) A method of synthesizing a substantially pure, water soluble        polymer of paragraph 18), said method comprising the steps of:        -   a) reacting the substantially pure, linear polymer,            substituted at the first terminus with a function R₂-M₂,            with a selected modifying reagent in form of the            phosphoramidite derivative under conditions facilitating the            quantitative conversion of the mono substituted polymer to            the double modified polymer.        -   b) isolation of the double modified polymer by precipitation            or crystallization.

    -   29) The use of any material of paragraph 1) to paragraph 28) for        formation of a conjugate between this material and a        biologically active molecule, wherein said biologically active        molecule is selected from the group consisting of enzymes,        peptides, polypeptides, nucleotides, oligonucleotides,        polynucleotides and low molecular weight drugs.

OTHER EMBODIMENTS

It is to be understood that while the invention has been described inconjunction with the detailed description thereof, the foregoingdescription is intended to illustrate and not limit the scope of theinvention, which is defined by the scope of the appended claims. Otheraspects, advantages, and modifications are within the scope of thefollowing claims.

1. (canceled)
 2. A method of making a compound comprising awater-soluble, non-peptidic, and non-nucleotidic polymer backbone havingat least one terminus covalently bonded to a structure of formula (1):

or a salt thereof, wherein: A is the point of covalent bonding to theterminus of the polymer backbone; E is O; K is selected from the groupconsisting of: alkylene, alkyleneoxyalkylene, and oligomericalkyleneoxyalkylene; G is selected from the group consisting of:hydrogen, alkoxy, and a hydrophobic separation handle; Z¹ is O; Z² is O;L is selected from the group consisting of: a divalent radical of anucleoside, alkylene, alkyleneoxyalkylene, oligomericalkyleneoxyalkylene, and unsubstituted and substituted arylene; M is aprotected group that when deprotected is reactive with a biologicallyactive molecule, a group reactive with a biologically active molecule; Ris absent or selected from the group consisting of: hydrogen, aprotecting group, a hydrophobic separation handle, or an activatinggroup; R¹ is absent or a hydrophobic separation handle; wherein when Mis a protected group that when deprotected is reactive with abiologically active molecule, then R is a protecting group or ahydrophobic separation handle; wherein when M is a group reactive with abiologically active molecule, R is absent, hydrogen, or an activatinggroup; and wherein only one of R, R¹, and G can be a hydrophobicseparation handle, said method comprising: a) contacting awater-soluble, non-peptidic, and non-nucleotidic polymer, in awater-free solvent, with a reagent of formula (4):

wherein: R⁵ and R⁶ independently from each other represent C₁-C₆-alkylor R⁵ and R⁶ jointly form a 5- or 6-membered ring with the N to whichthey are bonded; and K, G, Z¹, Z², L, M, R, and R¹ are as defined forformula (1); b) adding an activating reagent; and c) adding an oxidizingreagent, wherein the P is oxidized from P⁺³ to P⁺⁵, to obtain thecompound comprising the water-soluble, non-peptidic, and non-nucleotidicpolymer backbone having at least one terminus covalently bonded to thestructure of formula (1).
 3. The method of claim 2, wherein R is aprotecting group.
 4. The method of claim 3, wherein the method furthercomprises purifying the protected polymer by chromatography.
 5. Themethod of claim 4, wherein the method further comprises removing theprotecting group.
 6. The method of claim 2, wherein said activatingreagent is selected from the group consisting of: tetrazole,2-ethylthiotetrazole, 2-bezylthiotetrazole, 4,5-dicyanoimidazole,Activator 42, pyridinium hydrochloride, and pyridinium trifluoroacetate.7. The method of claim 2, wherein said oxidizing reagent is selectedfrom a group consisting of: iodine, hydrogen peroxide, t-butyl hydrogenperoxide, acetone peroxide, sulfur, and thiuram disulfide.
 8. The methodof claim 2, wherein the ratio of the polymer to the compound of formula(4) is from about 1:10 to about 10:1.
 9. The method of claim 2, whereinsaid polymer backbone is selected from the group consisting ofpoly(alkylene glycol), poly(oxyethylated polyol), poly(olefinicalcohol), poly(α-hydroxy acid), poly(vinyl alcohol), polyoxazoline, andcopolymers.
 10. The method of claim 9, wherein said polymer backbone ispoly(ethylene glycol).
 11. The method of claim 10, wherein saidpoly(ethylene glycol) has an average molecular weight from about 500 Dato about 100,000 Da.
 12. The method of claim 2, wherein said groupreactive with a biologically active molecule is selected from the groupconsisting of: hydroxyl, amine, thiol, carboxyl, aldehyde, glyoxal,dione, alkenyl, alkynyl, alkedienyl, azide, acrylamide, vinyl sulfone,hydrazide, aminoxy, maleimide, dithiopyridine, iodoacetamide.
 13. Themethod of claim 2, wherein K is selected from the group consisting of:methylene, ethylene, propylene, isopropylene, butylene, isobutylene,sec-butylene, tert-butylene, and hexylene, or a residue from diethyleneglycol, triethylene glycol, tetraethylene glycol or hexaethylene glycol.14. The method of claim 2, wherein G is a substituted or unsubstitutedtrityloxy.
 15. The method of claim 2, wherein L is a substituted orunsubstituted C₁-C₁₂ alkylene.
 16. The method of claim 2, wherein R isselected from the group consisting of: trityl, monoalkoxytrityl,dialkoxytrityl, pixyl, alkoxypixyl, fluorenylmethyloxycarbonyl,trifluoroacetyl, acetal, and cyclic acetal.
 17. The method of claim 2,wherein said group reactive with a biologically active molecule iscarboxyl and R is absent or selected from the group consisting of:chlorotrityl, trityl, N-hydroxysuccinimidyl, p-nitrophenyl,pentachlorophenyl, and an unsubstituted C₁-C₁₈ alkyl.
 18. A compound offormula (4):

or a salt thereof, wherein: R⁵ and R⁶ independently from each otherrepresent C₁-C₆-alkyl or R⁵ and R⁶ jointly form a 5- or 6-membered ringwith the N to which they are bonded; K is selected from the groupconsisting of: alkylene, alkyleneoxyalkylene, and oligomeric alkyleneoxyalkylene; G is selected from the group consisting of: hydrogen, alkoxy,and a hydrophobic separation handle; Z¹ is O; Z² is O; L is selectedfrom the group consisting of: a divalent radical of a nucleoside,alkylene, alkyleneoxyalkylene, oligomeric alkyleneoxyalkylene, andunsubstituted and substituted arylene; M is a protected group that whendeprotected is reactive with a biologically active molecule, a groupreactive with a biologically active molecule; R is absent or selectedfrom the group consisting of: hydrogen, a protecting group, ahydrophobic separation handle, or an activating group; R¹ is absent or ahydrophobic separation handle; wherein when M is a protected group thatwhen deprotected is reactive with a biologically active molecule, then Ris a protecting group or a hydrophobic separation handle; wherein when Mis a group reactive with a biologically active molecule, R is absent,hydrogen, or an activating group; and wherein only one of R, R¹, and Gcan be a hydrophobic separation handle.
 19. The compound of claim 18,wherein K is selected from the group consisting of: methylene, ethylene,propylene, isopropylene, butylene, isobutylene, sec-butylene,tert-butylene, and hexylene, or a residue from diethylene glycol,triethylene glycol, tetraethylene glycol or hexaethylene glycol.
 20. Thecompound of claim 18, wherein G is a substituted or unsubstitutedtrityloxy.
 21. The compound of claim 18, wherein L is a substituted orunsubstituted C₁-C₁₂ alkylene.